diff --git a/constructor/construct.py b/constructor/construct.py
index 210c157c5..9cad94a1e 100644
--- a/constructor/construct.py
+++ b/constructor/construct.py
@@ -746,10 +746,10 @@ def yamlize(data, directory, content_filter):
         if ('{{' not in data) and ('{%' not in data):
             raise UnableToParse(original=e)
         try:
-            from constructor.jinja import render_jinja
+            from constructor.jinja import render_jinja_for_input_file
         except ImportError as ex:
             raise UnableToParseMissingJinja2(original=ex)
-        data = render_jinja(data, directory, content_filter)
+        data = render_jinja_for_input_file(data, directory, content_filter)
         return yaml.load(data)
 
 
diff --git a/constructor/header.sh b/constructor/header.sh
index fc7434435..351cbad06 100644
--- a/constructor/header.sh
+++ b/constructor/header.sh
@@ -1,28 +1,28 @@
 #!/bin/sh
 #
-# Created by constructor __CONSTRUCTOR_VERSION__
+# Created by constructor {{ constructor_version }}
 #
-# NAME:  __NAME__
-# VER:   __VERSION__
-# PLAT:  __PLAT__
-# MD5:   __MD5__
+# NAME:  {{ installer_name }}
+# VER:   {{ installer_version }}
+# PLAT:  {{ installer_platform }}
+# MD5:   {{ installer_md5 }}
 
 set -eu
 
-#if osx
+{%- if osx %}
 unset DYLD_LIBRARY_PATH DYLD_FALLBACK_LIBRARY_PATH
-#else
+{%- else %}
 export OLD_LD_LIBRARY_PATH="${LD_LIBRARY_PATH:-}"
 unset LD_LIBRARY_PATH
-#endif
+{%- endif %}
 
 if ! echo "$0" | grep '\.sh$' > /dev/null; then
     printf 'Please run using "bash"/"dash"/"sh"/"zsh", but not "." or "source".\n' >&2
-    return 1
+    exit 1
 fi
 
-#if osx and min_osx_version
-min_osx_version="__MIN_OSX_VERSION__"
+{%- if osx and min_osx_version %}
+min_osx_version="{{ min_osx_version }}"
 system_osx_version="${CONDA_OVERRIDE_OSX:-$(SYSTEM_VERSION_COMPAT=0 sw_vers -productVersion)}"
 # shellcheck disable=SC2183 disable=SC2046
 int_min_osx_version="$(printf "%02d%02d%02d" $(echo "$min_osx_version" | sed 's/\./ /g'))"
@@ -32,9 +32,8 @@ if [ "$int_system_osx_version" -lt "$int_min_osx_version" ]; then
     echo "Installer requires macOS >=${min_osx_version}, but system has ${system_osx_version}."
     exit 1
 fi
-#endif
-#if linux and min_glibc_version
-min_glibc_version="__MIN_GLIBC_VERSION__"
+{%- elif linux and min_glibc_version %}
+min_glibc_version="{{ min_glibc_version }}"
 system_glibc_version="${CONDA_OVERRIDE_GLIBC:-}"
 if [ "${system_glibc_version}" = "" ]; then
     case "$(ldd --version 2>&1)" in
@@ -67,36 +66,28 @@ if [ "$int_system_glibc_version" -lt "$int_min_glibc_version" ]; then
     echo "Installer requires GLIBC >=${min_glibc_version}, but system has ${system_glibc_version}."
     exit 1
 fi
-#endif
+{%- endif %}
 
 # Export variables to make installer metadata available to pre/post install scripts
 # NOTE: If more vars are added, make sure to update the examples/scripts tests too
 
-_SCRIPT_ENV_VARIABLES_=''  # Templated extra environment variable(s)
-export INSTALLER_NAME='__NAME__'
-export INSTALLER_VER='__VERSION__'
-export INSTALLER_PLAT='__PLAT__'
+{{ script_env_variables }}
+export INSTALLER_NAME='{{ installer_name }}'
+export INSTALLER_VER='{{ installer_version }}'
+export INSTALLER_PLAT='{{ installer_platform }}'
 export INSTALLER_TYPE="SH"
 
 THIS_DIR=$(DIRNAME=$(dirname "$0"); cd "$DIRNAME"; pwd)
 THIS_FILE=$(basename "$0")
 THIS_PATH="$THIS_DIR/$THIS_FILE"
-PREFIX="__DEFAULT_PREFIX__"
-#if batch_mode
-BATCH=1
-#else
-BATCH=0
-#endif
+PREFIX="{{ default_prefix }}"
+BATCH={{ 1 if batch_mode else 0 }}
 FORCE=0
-#if keep_pkgs
-KEEP_PKGS=1
-#else
-KEEP_PKGS=0
-#endif
+KEEP_PKGS={{ 1 if keep_pkgs else 0 }}
 SKIP_SCRIPTS=0
-#if enable_shortcuts == "true"
+{%- if enable_shortcuts == "true" %}
 SKIP_SHORTCUTS=0
-#endif
+{%- endif %}
 TEST=0
 REINSTALL=0
 USAGE="
@@ -104,41 +95,41 @@ usage: $0 [options]
 
 Installs ${INSTALLER_NAME} ${INSTALLER_VER}
 
-#if batch_mode
+{%- if batch_mode %}
 -i           run install in interactive mode
-#else
+{%- else %}
 -b           run install in batch mode (without manual intervention),
              it is expected the license terms (if any) are agreed upon
-#endif
+{%- endif %}
 -f           no error if install prefix already exists
 -h           print this help message and exit
-#if not keep_pkgs
+{%- if not keep_pkgs %}
 -k           do not clear the package cache after installation
-#endif
-#if check_path_spaces
+{%- endif %}
+{%- if check_path_spaces %}
 -p PREFIX    install prefix, defaults to $PREFIX, must not contain spaces.
-#else
+{%- else %}
 -p PREFIX    install prefix, defaults to $PREFIX
-#endif
+{%- endif %}
 -s           skip running pre/post-link/install scripts
-#if enable_shortcuts == 'true'
+{%- if enable_shortcuts == 'true' %}
 -m           disable the creation of menu items / shortcuts
-#endif
+{%- endif %}
 -u           update an existing installation
-#if has_conda
+{%- if has_conda %}
 -t           run package tests after installation (may install conda-build)
-#endif
+{%- endif %}
 "
 
 # We used to have a getopt version here, falling back to getopts if needed
 # However getopt is not standardized and the version on Mac has different
 # behaviour. getopts is good enough for what we need :)
 # More info: https://unix.stackexchange.com/questions/62950/
-#if enable_shortcuts == "true"
+{%- if enable_shortcuts == "true" %}
 while getopts "bifhkp:smut" x; do
-#else
+{%- else %}
 while getopts "bifhkp:sut" x; do
-#endif
+{%- endif %}
     case "$x" in
         h)
             printf "%s\\n" "$USAGE"
@@ -162,19 +153,19 @@ while getopts "bifhkp:sut" x; do
         s)
             SKIP_SCRIPTS=1
             ;;
-#if enable_shortcuts == "true"
+{%- if enable_shortcuts == "true" %}
         m)
             SKIP_SHORTCUTS=1
             ;;
-#endif
+{%- endif %}
         u)
             FORCE=1
             ;;
-#if has_conda
+{%- if has_conda %}
         t)
             TEST=1
             ;;
-#endif
+{%- endif %}
         ?)
             printf "ERROR: did not recognize option '%s', please try -h\\n" "$x"
             exit 1
@@ -194,7 +185,7 @@ fi
 
 if [ "$BATCH" = "0" ] # interactive mode
 then
-#if x86 and not x86_64
+{%- if x86 and not x86_64 %}
     if [ "$(uname -m)" = "x86_64" ]; then
         printf "WARNING:\\n"
         printf "    Your system is x86_64, but you are trying to install an x86 (32-bit)\\n"
@@ -212,9 +203,7 @@ then
             exit 2
         fi
     fi
-#endif
-
-#if x86_64
+{%- elif x86_64 %}
     if [ "$(uname -m)" != "x86_64" ]; then
         printf "WARNING:\\n"
         printf "    Your operating system appears not to be 64-bit, but you are trying to\\n"
@@ -229,9 +218,7 @@ then
             exit 2
         fi
     fi
-#endif
-
-#if ppc64le
+{%- elif ppc64le %}
     if [ "$(uname -m)" != "ppc64le" ]; then
         printf "WARNING:\\n"
         printf "    Your machine hardware does not appear to be Power8 (little endian), \\n"
@@ -246,9 +233,7 @@ then
             exit 2
         fi
     fi
-#endif
-
-#if s390x
+{%- elif s390x %}
     if [ "$(uname -m)" != "s390x" ]; then
         printf "WARNING:\\n"
         printf "    Your machine hardware does not appear to be s390x (big endian), \\n"
@@ -263,9 +248,7 @@ then
             exit 2
         fi
     fi
-#endif
-
-#if aarch64
+{%- elif aarch64 %}
     if [ "$(uname -m)" != "aarch64" ]; then
         printf "WARNING:\\n"
         printf "    Your machine hardware does not appear to be aarch64, \\n"
@@ -280,9 +263,9 @@ then
             exit 2
         fi
     fi
-#endif
+{%- endif %}
 
-#if osx
+{%- if osx %}
     if [ "$(uname)" != "Darwin" ]; then
         printf "WARNING:\\n"
         printf "    Your operating system does not appear to be macOS, \\n"
@@ -297,9 +280,7 @@ then
             exit 2
         fi
     fi
-#endif
-
-#if linux
+{%- elif linux %}
     if [ "$(uname)" != "Linux" ]; then
         printf "WARNING:\\n"
         printf "    Your operating system does not appear to be Linux, \\n"
@@ -314,11 +295,11 @@ then
             exit 2
         fi
     fi
-#endif
+{%- endif %}
 
     printf "\\n"
     printf "Welcome to %s %s\\n" "${INSTALLER_NAME}" "${INSTALLER_VER}"
-#if has_license
+{%- if has_license %}
     printf "\\n"
     printf "In order to continue the installation process, please review the license\\n"
     printf "agreement.\\n"
@@ -330,7 +311,7 @@ then
       pager="more"
     fi
     "$pager" <<'EOF'
-__LICENSE__
+{{ license }}
 EOF
     printf "\\n"
     printf "Do you accept the license terms? [yes|no]\\n"
@@ -349,7 +330,7 @@ EOF
         printf "The license agreement wasn't approved, aborting installation.\\n"
         exit 2
     fi
-#endif
+{%- endif %}
 
     printf "\\n"
     printf "%s will now be installed into this location:\\n" "${INSTALLER_NAME}"
@@ -362,7 +343,7 @@ EOF
     printf "[%s] >>> " "$PREFIX"
     read -r user_prefix
     if [ "$user_prefix" != "" ]; then
-#if check_path_spaces is True
+{%- if check_path_spaces %}
         case "$user_prefix" in
             *\ * )
                 printf "ERROR: Cannot install into directories with spaces\\n" >&2
@@ -372,20 +353,20 @@ EOF
                 eval PREFIX="$user_prefix"
                 ;;
         esac
-#else
+{%- else %}
         PREFIX="$user_prefix"
-#endif
+{%- endif %}
     fi
 fi # !BATCH
 
-#if check_path_spaces is True
+{%- if check_path_spaces %}
 case "$PREFIX" in
     *\ * )
         printf "ERROR: Cannot install into directories with spaces\\n" >&2
         exit 1
         ;;
 esac
-#endif
+{%- endif %}
 
 if [ "$FORCE" = "0" ] && [ -e "$PREFIX" ]; then
     printf "ERROR: File or directory already exists: '%s'\\n" "$PREFIX" >&2
@@ -395,7 +376,7 @@ elif [ "$FORCE" = "1" ] && [ -e "$PREFIX" ]; then
     REINSTALL=1
 fi
 
-total_installation_size_kb="__TOTAL_INSTALLATION_SIZE_KB__"
+total_installation_size_kb="{{ total_installation_size_kb }}"
 total_installation_size_mb="$(( total_installation_size_kb / 1024 ))"
 if ! mkdir -p "$PREFIX"; then
     printf "ERROR: Could not create directory: '%s'.\\n" "$PREFIX" >&2
@@ -445,20 +426,16 @@ last_line=$(grep -anm 1 '^@@END_HEADER@@' "$THIS_PATH" | sed 's/:.*//')
 # the start of the first payload, in bytes, indexed from zero
 boundary0=$(head -n "${last_line}" "${THIS_PATH}" | wc -c | sed 's/ //g')
 # the start of the second payload / the end of the first payload, plus one
-boundary1=$(( boundary0 + __FIRST_PAYLOAD_SIZE__ ))
+boundary1=$(( boundary0 + {{ first_payload_size }} ))
 # the end of the second payload, plus one
-boundary2=$(( boundary1 + __SECOND_PAYLOAD_SIZE__ ))
+boundary2=$(( boundary1 + {{ second_payload_size }} ))
 
 # verify the MD5 sum of the tarball appended to this header
-#if osx
-MD5=$(extract_range "${boundary0}" "${boundary2}" | md5)
-#else
-MD5=$(extract_range "${boundary0}" "${boundary2}" | md5sum -)
-#endif
+MD5=$(extract_range "${boundary0}" "${boundary2}" | {{ "md5" if osx else "md5sum -" }})
 
-if ! echo "$MD5" | grep __MD5__ >/dev/null; then
+if ! echo "$MD5" | grep {{ installer_md5 }} >/dev/null; then
     printf "WARNING: md5sum mismatch of tar archive\\n" >&2
-    printf "expected: __MD5__\\n" >&2
+    printf "expected: {{ installer_md5 }}\\n" >&2
     printf "     got: %s\\n" "$MD5" >&2
 fi
 
@@ -483,13 +460,13 @@ mkdir -p "$TMP"
 # micromamba needs an existing pkgs_dir to operate even offline,
 # but we haven't created $PREFIX/pkgs yet... give it a temp location
 # shellcheck disable=SC2050
-if [ "__VIRTUAL_SPECS__" != "" ]; then
-    echo "Checking virtual specs compatibility:" __VIRTUAL_SPECS__
+{%- if virtual_specs %}
+    echo "Checking virtual specs compatibility:" {{ virtual_specs }}
     CONDA_QUIET="$BATCH" \
     CONDA_SOLVER="classic" \
     CONDA_PKGS_DIRS="$(mktemp -d)" \
-    "$CONDA_EXEC" create --dry-run --prefix "$PREFIX/envs/_virtual_specs_checks" --offline __VIRTUAL_SPECS__ __NO_RCS_ARG__
-fi
+    "$CONDA_EXEC" create --dry-run --prefix "$PREFIX/envs/_virtual_specs_checks" --offline {{ virtual_specs }} {{ no_rcs_arg }}
+{%- endif %}
 
 # Create $PREFIX/.nonadmin if the installation didn't require superuser permissions
 if [ "$(id -u)" -ne 0 ]; then
@@ -498,7 +475,7 @@ fi
 
 # the second binary payload: the tarball of packages
 printf "Unpacking payload ...\n"
-extract_range $boundary1 $boundary2 | \
+extract_range "${boundary1}" "${boundary2}" | \
     CONDA_QUIET="$BATCH" "$CONDA_EXEC" constructor --extract-tarball --prefix "$PREFIX"
 
 PRECONDA="$PREFIX/preconda.tar.bz2"
@@ -509,26 +486,22 @@ rm -f "$PRECONDA"
 CONDA_QUIET="$BATCH" \
 "$CONDA_EXEC" constructor --prefix "$PREFIX" --extract-conda-pkgs || exit 1
 
-#The templating doesn't support nested if statements
-#if has_pre_install
+{%- if has_pre_install %}
 if [ "$SKIP_SCRIPTS" = "1" ]; then
     export INST_OPT='--skip-scripts'
     printf "WARNING: skipping pre_install.sh by user request\\n" >&2
 else
     export INST_OPT=''
-#endif
-#if has_pre_install and direct_execute_pre_install
+    {%- if direct_execute_pre_install %}
     if ! "$PREFIX/pkgs/pre_install.sh"; then
-#endif
-#if has_pre_install and not direct_execute_pre_install
+    {%- else %}
     if ! sh "$PREFIX/pkgs/pre_install.sh"; then
-#endif
-#if has_pre_install
+    {%- endif %}
         printf "ERROR: executing pre_install.sh failed\\n" >&2
         exit 1
     fi
 fi
-#endif
+{%- endif %}
 
 MSGS="$PREFIX/.messages.txt"
 touch "$MSGS"
@@ -544,33 +517,30 @@ test -d ~/.conda || mkdir -p ~/.conda >/dev/null 2>/dev/null || test -d ~/.conda
 
 printf "\nInstalling base environment...\n\n"
 
-#if enable_shortcuts == "true"
+{%- if enable_shortcuts == "true" %}
 if [ "$SKIP_SHORTCUTS" = "1" ]; then
     shortcuts="--no-shortcuts"
 else
-    shortcuts="__SHORTCUTS__"
+    shortcuts="{{ shortcuts }}"
 fi
-#endif
-#if enable_shortcuts == "false"
+{%- elif enable_shortcuts == "false" %}
 shortcuts="--no-shortcuts"
-#endif
-#if enable_shortcuts == "incompatible"
+{%- elif enable_shortcuts == "incompatible" %}
 shortcuts=""
-#endif
+{%- endif %}
 
 # shellcheck disable=SC2086
 CONDA_ROOT_PREFIX="$PREFIX" \
-CONDA_REGISTER_ENVS="__REGISTER_ENVS__" \
+CONDA_REGISTER_ENVS="{{ register_envs }}" \
 CONDA_SAFETY_CHECKS=disabled \
 CONDA_EXTRA_SAFETY_CHECKS=no \
-CONDA_CHANNELS="__CHANNELS__" \
+CONDA_CHANNELS="{{ channels }}" \
 CONDA_PKGS_DIRS="$PREFIX/pkgs" \
 CONDA_QUIET="$BATCH" \
-"$CONDA_EXEC" install --offline --file "$PREFIX/pkgs/env.txt" -yp "$PREFIX" $shortcuts __NO_RCS_ARG__ || exit 1
+"$CONDA_EXEC" install --offline --file "$PREFIX/pkgs/env.txt" -yp "$PREFIX" $shortcuts {{ no_rcs_arg }} || exit 1
 rm -f "$PREFIX/pkgs/env.txt"
 
-#The templating doesn't support nested if statements
-#if has_conda
+{%- if has_conda %}
 mkdir -p "$PREFIX/envs"
 for env_pkgs in "${PREFIX}"/pkgs/envs/*/; do
     env_name=$(basename "${env_pkgs}")
@@ -584,10 +554,9 @@ for env_pkgs in "${PREFIX}"/pkgs/envs/*/; do
         env_channels=$(cat "${env_pkgs}channels.txt")
         rm -f "${env_pkgs}channels.txt"
     else
-        env_channels="__CHANNELS__"
+        env_channels="{{ channels }}"
     fi
-#endif
-#if has_conda and enable_shortcuts == "true"
+    {%- if enable_shortcuts == "true" %}
     if [ "$SKIP_SHORTCUTS" = "1" ]; then
         env_shortcuts="--no-shortcuts"
     else
@@ -595,28 +564,25 @@ for env_pkgs in "${PREFIX}"/pkgs/envs/*/; do
         env_shortcuts=$(cat "${env_pkgs}shortcuts.txt")
         rm -f "${env_pkgs}shortcuts.txt"
     fi
-#endif
-#if has_conda and enable_shortcuts == "false"
+    {%- elif enable_shortcuts == "false" %}
     env_shortcuts="--no-shortcuts"
-#endif
-#if has_conda and enable_shortcuts == "incompatible"
+    {%- elif enable_shortcuts == "incompatible" %}
     env_shortcuts=""
-#endif
-#if has_conda
+    {%- endif %}
     # shellcheck disable=SC2086
     CONDA_ROOT_PREFIX="$PREFIX" \
-    CONDA_REGISTER_ENVS="__REGISTER_ENVS__" \
+    CONDA_REGISTER_ENVS="{{ register_envs }}" \
     CONDA_SAFETY_CHECKS=disabled \
     CONDA_EXTRA_SAFETY_CHECKS=no \
     CONDA_CHANNELS="$env_channels" \
     CONDA_PKGS_DIRS="$PREFIX/pkgs" \
     CONDA_QUIET="$BATCH" \
-    "$CONDA_EXEC" install --offline --file "${env_pkgs}env.txt" -yp "$PREFIX/envs/$env_name" $env_shortcuts __NO_RCS_ARG__ || exit 1
+    "$CONDA_EXEC" install --offline --file "${env_pkgs}env.txt" -yp "$PREFIX/envs/$env_name" $env_shortcuts {{ no_rcs_arg }} || exit 1
     rm -f "${env_pkgs}env.txt"
 done
-#endif
+{%- endif %}
 
-__INSTALL_COMMANDS__
+{{ install_commands }}
 
 POSTCONDA="$PREFIX/postconda.tar.bz2"
 CONDA_QUIET="$BATCH" \
@@ -627,23 +593,20 @@ export TMP="$TMP_BACKUP"
 
 
 #The templating doesn't support nested if statements
-#if has_post_install
+{%- if has_post_install %}
 if [ "$SKIP_SCRIPTS" = "1" ]; then
     printf "WARNING: skipping post_install.sh by user request\\n" >&2
 else
-#endif
-#if has_post_install and direct_execute_post_install
+    {%- if direct_execute_post_install %}
     if ! "$PREFIX/pkgs/post_install.sh"; then
-#endif
-#if has_post_install and not direct_execute_post_install
+    {%- else %}
     if ! sh "$PREFIX/pkgs/post_install.sh"; then
-#endif
-#if has_post_install
+    {%- endif %}
         printf "ERROR: executing post_install.sh failed\\n" >&2
         exit 1
     fi
 fi
-#endif
+{%- endif %}
 
 if [ -f "$MSGS" ]; then
   cat "$MSGS"
@@ -658,7 +621,7 @@ else
 fi
 
 cat <<'EOF'
-__CONCLUSION_TEXT__
+{{ conclusion_text }}
 EOF
 
 if [ "${PYTHONPATH:-}" != "" ]; then
@@ -671,14 +634,8 @@ if [ "${PYTHONPATH:-}" != "" ]; then
 fi
 
 if [ "$BATCH" = "0" ]; then
-#if initialize_conda is True and initialize_by_default is True
-    DEFAULT=yes
-#endif
-#if initialize_conda is True and initialize_by_default is False
-    DEFAULT=no
-#endif
-
-#if has_conda and initialize_conda is True
+{%- if has_conda and initialize_conda %}
+    DEFAULT={{ 'yes' if initialize_by_default else 'no' }}
     # Interactive mode.
 
     printf "Do you wish to update your shell profile to automatically initialize conda?\\n"
@@ -721,13 +678,13 @@ if [ "$BATCH" = "0" ]; then
             esac
         fi
     fi
-#endif
+{%- endif %}
 
     printf "Thank you for installing %s!\\n" "${INSTALLER_NAME}"
 fi # !BATCH
 
 
-#if has_conda
+{%- if has_conda %}
 if [ "$TEST" = "1" ]; then
     printf "INFO: Running package tests in a subshell\\n"
     NFAILS=0
@@ -760,7 +717,7 @@ if [ "$TEST" = "1" ]; then
         exit $NFAILS
     fi
 fi
-#endif
+{%- endif %}
 
 exit 0
 # shellcheck disable=SC2317
diff --git a/constructor/jinja.py b/constructor/jinja.py
index 41f65ee2a..2d46d861f 100644
--- a/constructor/jinja.py
+++ b/constructor/jinja.py
@@ -1,8 +1,9 @@
 import os
 
-from jinja2 import BaseLoader, Environment, FileSystemLoader, TemplateError
+from jinja2 import BaseLoader, Environment, FileSystemLoader, StrictUndefined, TemplateError
 
-from constructor.exceptions import UnableToParse
+from . import __version__
+from .exceptions import UnableToParse
 
 
 # adapted from conda-build
@@ -25,7 +26,7 @@ def get_source(self, environment, template):
 
 
 # adapted from conda-build
-def render_jinja(data, directory, content_filter):
+def render_jinja_for_input_file(data, directory, content_filter):
     loader = FilteredLoader(FileSystemLoader(directory), content_filter)
     env = Environment(loader=loader)
     env.globals['environ'] = os.environ.copy()
@@ -36,3 +37,13 @@ def render_jinja(data, directory, content_filter):
     except TemplateError as ex:
         raise UnableToParse(original=ex)
     return rendered
+
+
+def render_template(text, **kwargs):
+    env = Environment(keep_trailing_newline=True, undefined=StrictUndefined)
+    env.globals["constructor_version"] = __version__
+    try:
+        template = env.from_string(text)
+        return template.render(**kwargs)
+    except TemplateError as ex:
+        raise UnableToParse(original=ex) from ex
diff --git a/constructor/nsis/main.nsi.tmpl b/constructor/nsis/main.nsi.tmpl
index 3bb66380e..4e2722194 100644
--- a/constructor/nsis/main.nsi.tmpl
+++ b/constructor/nsis/main.nsi.tmpl
@@ -7,11 +7,11 @@
 
 Unicode true
 
-#if enable_debugging is True
+{%- if enable_debugging %}
 # Special logging build needed for ENABLE_LOGGING
 # See https://nsis.sourceforge.io/Special_Builds
 !define ENABLE_LOGGING
-#endif
+{%- endif %}
 
 # Comes from https://nsis.sourceforge.io/Logging:Enable_Logs_Quickly
 !define LogSet "!insertmacro LogSetMacro"
@@ -67,26 +67,26 @@ var /global StdOutHandleSet
 
 !include "Utils.nsh"
 
-!define NAME __NAME__
-!define VERSION __VERSION__
-!define COMPANY __COMPANY__
-!define ARCH __ARCH__
-!define PLATFORM __PLATFORM__
-!define CONSTRUCTOR_VERSION __CONSTRUCTOR_VERSION__
-!define PY_VER __PY_VER__
-!define PYVERSION_JUSTDIGITS __PYVERSION_JUSTDIGITS__
-!define PYVERSION __PYVERSION__
-!define PYVERSION_MAJOR __PYVERSION_MAJOR__
-!define DEFAULT_PREFIX __DEFAULT_PREFIX__
-!define DEFAULT_PREFIX_DOMAIN_USER __DEFAULT_PREFIX_DOMAIN_USER__
-!define DEFAULT_PREFIX_ALL_USERS __DEFAULT_PREFIX_ALL_USERS__
-!define PRE_INSTALL_DESC __PRE_INSTALL_DESC__
-!define POST_INSTALL_DESC __POST_INSTALL_DESC__
-!define ENABLE_SHORTCUTS __ENABLE_SHORTCUTS__
-!define SHOW_REGISTER_PYTHON __SHOW_REGISTER_PYTHON__
-!define SHOW_ADD_TO_PATH __SHOW_ADD_TO_PATH__
+!define NAME {{ installer_name }}
+!define VERSION {{ installer_version }}
+!define COMPANY {{ company }}
+!define ARCH {{ arch }}
+!define PLATFORM {{ installer_platform }}
+!define CONSTRUCTOR_VERSION {{ constructor_version }}
+!define PY_VER {{ py_ver }}
+!define PYVERSION_JUSTDIGITS {{ pyversion_justdigits }}
+!define PYVERSION {{ pyversion }}
+!define PYVERSION_MAJOR {{ pyversion_major }}
+!define DEFAULT_PREFIX {{ default_prefix }}
+!define DEFAULT_PREFIX_DOMAIN_USER {{ default_prefix_domain_user }}
+!define DEFAULT_PREFIX_ALL_USERS {{ default_prefix_all_users }}
+!define PRE_INSTALL_DESC {{ pre_install_desc }}
+!define POST_INSTALL_DESC {{ post_install_desc }}
+!define ENABLE_SHORTCUTS {{ enable_shortcuts }}
+!define SHOW_REGISTER_PYTHON {{ show_register_python }}
+!define SHOW_ADD_TO_PATH {{ show_add_to_path }}
 !define PRODUCT_NAME "${NAME} ${VERSION} (${ARCH})"
-!define UNINSTALL_NAME "@UNINSTALL_NAME@"
+!define UNINSTALL_NAME "{{ UNINSTALL_NAME }}"
 !define UNINSTREG "SOFTWARE\Microsoft\Windows\CurrentVersion\
                    \Uninstall\${UNINSTALL_NAME}"
 
@@ -130,7 +130,7 @@ CRCCheck On
 
 # Basic options
 Name "${PRODUCT_NAME}"
-OutFile __OUTFILE__
+OutFile {{ outfile }}
 ShowInstDetails "hide"
 ShowUninstDetails "hide"
 # This installer contains tar.bz2 files, which are already compressed
@@ -147,33 +147,33 @@ VIAddVersionKey "CompanyName" "${COMPANY}"
 VIAddVersionKey "LegalCopyright" "(c) ${COMPANY}"
 VIAddVersionKey "FileDescription" "${NAME} Installer"
 VIAddVersionKey "Comments" "Created by constructor ${CONSTRUCTOR_VERSION}"
-VIProductVersion __VIPV__
+VIProductVersion {{ vipv }}
 BrandingText /TRIMLEFT "${COMPANY}"
 
 # Interface configuration
-!define MUI_ICON __ICONFILE__
-!define MUI_UNICON __ICONFILE__
+!define MUI_ICON {{ iconfile }}
+!define MUI_UNICON {{ iconfile }}
 !define MUI_HEADERIMAGE
-!define MUI_HEADERIMAGE_BITMAP __HEADERIMAGE__
-!define MUI_HEADERIMAGE_UNBITMAP __HEADERIMAGE__
+!define MUI_HEADERIMAGE_BITMAP {{ headerimage }}
+!define MUI_HEADERIMAGE_UNBITMAP {{ headerimage }}
 !define MUI_ABORTWARNING
 !define MUI_FINISHPAGE_NOAUTOCLOSE
 !define MUI_UNFINISHPAGE_NOAUTOCLOSE
-!define MUI_WELCOMEFINISHPAGE_BITMAP __WELCOMEIMAGE__
-!define MUI_UNWELCOMEFINISHPAGE_BITMAP __WELCOMEIMAGE__
+!define MUI_WELCOMEFINISHPAGE_BITMAP {{ welcomeimage }}
+!define MUI_UNWELCOMEFINISHPAGE_BITMAP {{ welcomeimage }}
 #!define MUI_CUSTOMFUNCTION_GUIINIT GuiInit
 
 # Pages
 #!define MUI_PAGE_CUSTOMFUNCTION_SHOW OnStartup
-#if custom_welcome
+{%- if custom_welcome %}
 # Custom welcome file(s)
-@CUSTOM_WELCOME_FILE@
-#else
+{{ CUSTOM_WELCOME_FILE }}
+{%- else %}
 !define MUI_PAGE_CUSTOMFUNCTION_PRE SkipPageIfUACInnerInstance
 !insertmacro MUI_PAGE_WELCOME
-#endif
+{%- endif %}
 !define MUI_PAGE_CUSTOMFUNCTION_PRE SkipPageIfUACInnerInstance
-!insertmacro MUI_PAGE_LICENSE __LICENSEFILE__
+!insertmacro MUI_PAGE_LICENSE {{ licensefile }}
 Page Custom InstModePage_Create InstModePage_Leave
 !define MUI_PAGE_CUSTOMFUNCTION_PRE DisableBackButtonIfUACInnerInstance
 !define MUI_PAGE_CUSTOMFUNCTION_LEAVE OnDirectoryLeave
@@ -182,22 +182,22 @@ Page Custom InstModePage_Create InstModePage_Leave
 Page Custom mui_AnaCustomOptions_Show
 !insertmacro MUI_PAGE_INSTFILES
 
-#if post_install_pages is True
-@POST_INSTALL_PAGES@
-#endif
+{%- if post_install_pages %}
+{{ POST_INSTALL_PAGES }}
+{%- endif %}
 
-#if with_conclusion_text is True
-!define MUI_FINISHPAGE_TITLE __CONCLUSION_TITLE__
+{%- if with_conclusion_text %}
+!define MUI_FINISHPAGE_TITLE {{ conclusion_title }}
 !define MUI_FINISHPAGE_TITLE_3LINES
-!define MUI_FINISHPAGE_TEXT __CONCLUSION_TEXT__
-#endif
+!define MUI_FINISHPAGE_TEXT {{ conclusion_text }}
+{%- endif %}
 
-#if custom_conclusion
+{%- if custom_conclusion %}
 # Custom conclusion file(s)
-@CUSTOM_CONCLUSION_FILE@
+{{ CUSTOM_CONCLUSION_FILE }}
 #else
 !insertmacro MUI_PAGE_FINISH
-#endif
+{%- endif %}
 
 
 !insertmacro MUI_UNPAGE_WELCOME
@@ -269,12 +269,7 @@ FunctionEnd
             $\n\
                 /InstallationType=AllUsers [default: JustMe]$\n\
                 /AddToPath=[0|1] [default: 0]$\n\
-#if keep_pkgs is True
-                /KeepPkgCache=[0|1] [default: 1]$\n\
-#endif
-#if keep_pkgs is False
-                /KeepPkgCache=[0|1] [default: 0]$\n\
-#endif
+                /KeepPkgCache=[0|1] [default: {{ 1 if keep_pkgs else 0 }}]$\n\
                 /RegisterPython=[0|1] [default: AllUsers: 1, JustMe: 0]$\n\
                 /NoRegistry=[0|1] [default: AllUsers: 0, JustMe: 0]$\n\
                 /NoScripts=[0|1] [default: 0]$\n\
@@ -332,7 +327,7 @@ FunctionEnd
     ClearErrors
     ${GetOptions} $ARGV "/KeepPkgCache=" $ARGV_KeepPkgCache
     ${If} ${Errors}
-        StrCpy $ARGV_KeepPkgCache "@KEEP_PKGS@"
+        StrCpy $ARGV_KeepPkgCache "{{ 1 if keep_pkgs else 0 }}"
     ${EndIf}
 
     ClearErrors
@@ -550,13 +545,13 @@ Function .onInit
     Push $R2
 
     InitPluginsDir
-    @TEMP_EXTRA_FILES@
+    {{ TEMP_EXTRA_FILES }}
     !insertmacro ParseCommandLineArgs
 
     # Select the correct registry to look at, depending
     # on whether it's a 32-bit or 64-bit installer
-    SetRegView @BITS@
-#if win64
+    SetRegView {{ BITS }}
+{%- if win64 %}
     # If we're a 64-bit installer, make sure it's 64-bit Windows
     ${IfNot} ${RunningX64}
         MessageBox MB_OK|MB_ICONEXCLAMATION \
@@ -566,7 +561,7 @@ Function .onInit
             /SD IDOK
         Abort
     ${EndIf}
-#endif
+{%- endif %}
 
     !insertmacro UAC_PageElevation_OnInit
     ${If} ${UAC_IsInnerInstance}
@@ -669,9 +664,9 @@ Function .onInit
             ${IfNot} ${UAC_IsAdmin}
                 MessageBox MB_ICONSTOP "Installation for all users requires an elevated prompt."
                 Abort
-            ${EndIF}
-        ${EndIF}
-    ${EndIF}
+            ${EndIf}
+        ${EndIf}
+    ${EndIf}
 
     ; /D was not used, add default based on install type
     ${If} $InstDir == ""
@@ -692,44 +687,23 @@ Function .onInit
     Call mui_AnaCustomOptions_InitDefaults
     # Override custom options with explicitly given values from contruct.yaml.
     # If initialize_by_default (register_python_default) is None, do nothing.
-#if initialize_conda is True and initialize_by_default is True
+{%- if initialize_conda %}
+    {%- if initialize_by_default %}
     ${If} $InstMode == ${JUST_ME}
         StrCpy $Ana_AddToPath_State ${BST_CHECKED}
-    ${EndIF}
-#endif
-#if initialize_conda is True and initialize_by_default is False
+    ${EndIf}
+    {%- else %}
     StrCpy $Ana_AddToPath_State ${BST_UNCHECKED}
-#endif
-#if register_python is True and register_python_default is True
-    StrCpy $Ana_RegisterSystemPython_State ${BST_CHECKED}
-#endif
-#if register_python is True and register_python_default is False
-    StrCpy $Ana_RegisterSystemPython_State ${BST_UNCHECKED}
-#endif
-#if check_path_length is True
-    StrCpy $CheckPathLength "1"
-#endif
-#if check_path_length is False
-    StrCpy $CheckPathLength "0"
-#endif
-#if keep_pkgs is True
-    StrCpy $Ana_ClearPkgCache_State ${BST_UNCHECKED}
-#endif
-#if keep_pkgs is False
-    StrCpy $Ana_ClearPkgCache_State ${BST_CHECKED}
-#endif
-#if pre_install_exists is True
-    StrCpy $Ana_PreInstall_State ${BST_CHECKED}
-#endif
-#if pre_install_exists is False
-    StrCpy $Ana_PreInstall_State ${BST_UNCHECKED}
-#endif
-#if post_install_exists is True
-    StrCpy $Ana_PostInstall_State ${BST_CHECKED}
-#endif
-#if post_install_exists is False
-    StrCpy $Ana_PostInstall_State ${BST_UNCHECKED}
-#endif
+    {%- endif %}
+{%- endif %}
+
+{%- if register_python %}
+    StrCpy $Ana_RegisterSystemPython_State {{ '${BST_CHECKED}' if register_python_default else '${BST_UNCHECKED}' }}
+{%- endif %}
+    StrCpy $CheckPathLength "{{ 1 if check_path_length else 0 }}"
+    StrCpy $Ana_ClearPkgCache_State {{ '${BST_UNCHECKED}' if keep_pkgs else '${BST_CHECKED}' }}
+    StrCpy $Ana_PreInstall_State {{ '${BST_CHECKED}' if pre_install_exists else '${BST_UNCHECKED}' }}
+    StrCpy $Ana_PostInstall_State {{ '${BST_CHECKED}' if post_install_exists else '${BST_UNCHECKED}' }}
 
     Call OnInit_Release
 
@@ -842,7 +816,7 @@ Function un.onInit
 
     # Select the correct registry to look at, depending
     # on whether it's a 32-bit or 64-bit installer
-    SetRegView @BITS@
+    SetRegView {{ BITS }}
 
     # Since the switch to a dual-mode installer (All Users/Just Me), the
     # uninstaller will inherit the requested execution level of the main
@@ -1021,22 +995,22 @@ Function OnDirectoryLeave
           StrCpy $R7 "$\n"
         ${EndIf}
         StrCpy $R8 "'Destination Folder' contains $R0 space$R1.$R7This can cause problems with several conda packages.$R7"
-#if check_path_spaces is True
+{%- if check_path_spaces %}
             StrCpy $R8 "$R8Please remove the space$R1 from the destination folder."
             StrCpy $R9 "Error"
-#else
+{%- else %}
             StrCpy $R8 "$R8Please consider removing the space$R1."
             StrCpy $R9 "Warning"
-#endif
+{%- endif %}
         # Show message box then take the user back to the Directory page.
         ${If} ${Silent}
             ${Print} "::$R9:: $R8"
         ${Else}
             MessageBox MB_OK|MB_ICONINFORMATION "$R9: $R8" /SD IDOK
         ${EndIf}
-#if check_path_spaces is True
+{%- if check_path_spaces %}
             abort
-#endif
+{%- endif %}
     NoSpaces:
     Pop $R7
     Pop $R8
@@ -1177,8 +1151,8 @@ Section "Install"
     ${EndIf}
 
     SetOutPath "$INSTDIR\Lib"
-    File "@NSIS_DIR@\_nsis.py"
-    File "@NSIS_DIR@\_system_path.py"
+    File "{{ NSIS_DIR }}\_nsis.py"
+    File "{{ NSIS_DIR }}\_system_path.py"
 
     # Resolve INSTDIR so that paths and registry keys do not contain '..' or similar strings.
     # $0 is empty if the directory doesn't exist, but the File commands should have created it already.
@@ -1189,13 +1163,13 @@ Section "Install"
     ${EndIf}
     StrCpy $INSTDIR $0
 
-#if has_license
+{%- if has_license %}
     SetOutPath "$INSTDIR"
-    File __LICENSEFILE__
+    File {{ licensefile }}
     ${Print} "By continuing this installation you are accepting this license agreement:"
-    ${Print} "$INSTDIR\@LICENSEFILENAME@"
+    ${Print} "$INSTDIR\{{ LICENSEFILENAME }}"
     ${Print} "Please run the installer in GUI mode to read the details.$\n"
-#endif
+{%- endif %}
 
     ${Print} "${NAME} will now be installed into this location:"
     ${Print} "$INSTDIR$\n"
@@ -1211,14 +1185,14 @@ Section "Install"
 
     # A conda-meta\history file is required for a valid conda prefix
     SetOutPath "$INSTDIR\conda-meta"
-    File __CONDA_HISTORY__
+    File {{ conda_history }}
 
     SetOutPath "$INSTDIR"
-    File __CONDA_EXE__
-    File __PRE_UNINSTALL__
+    File {{ conda_exe }}
+    File {{ pre_uninstall }}
 
     # Copy extra files (code generated on winexe.py)
-    @EXTRA_FILES@
+    {{ EXTRA_FILES }}
 
     ${If} $InstMode = ${JUST_ME}
         SetOutPath "$INSTDIR"
@@ -1227,16 +1201,16 @@ Section "Install"
     ${EndIf}
 
     SetOutPath "$INSTDIR\pkgs"
-    File __URLS_FILE__
-    File __URLS_TXT_FILE__
-#if pre_install_exists is True
-    File __PRE_INSTALL__
-#endif
-    File __POST_INSTALL__
-    File /nonfatal /r __INDEX_CACHE__
-    File /r __REPODATA_RECORD__
-
-    @SCRIPT_ENV_VARIABLES@
+    File {{ urls_file }}
+    File {{ urls_txt_file }}
+{%- if pre_install_exists %}
+    File {{ pre_install }}
+{%- endif %}
+    File {{ post_install }}
+    File /nonfatal /r {{ index_cache }}
+    File /r {{ repodata_record }}
+
+    {{ SCRIPT_ENV_VARIABLES }}
     System::Call 'kernel32::SetEnvironmentVariable(t,t)i("CONDA_SAFETY_CHECKS", "disabled").r0'
     System::Call 'kernel32::SetEnvironmentVariable(t,t)i("CONDA_EXTRA_SAFETY_CHECKS", "no").r0'
     System::Call 'kernel32::SetEnvironmentVariable(t,t)i("CONDA_ROOT_PREFIX", "$INSTDIR")".r0'
@@ -1256,22 +1230,22 @@ Section "Install"
         System::Call 'kernel32::SetEnvironmentVariable(t,t)i("INSTALLER_UNATTENDED", "0").r0'
     ${EndIf}
 
-    ${If} '@VIRTUAL_SPECS@' != ''
+    ${If} '{{ VIRTUAL_SPECS }}' != ''
     # We need to specify CONDA_SOLVER=classic for conda-standalone
     # to work around this bug in conda-libmamba-solver:
     # https://github.com/conda/conda-libmamba-solver/issues/480
     System::Call 'kernel32::SetEnvironmentVariable(t,t)i("CONDA_SOLVER", "classic").r0'
     SetDetailsPrint TextOnly
-    ${Print} "Checking virtual specs compatibility: @VIRTUAL_SPECS_DEBUG@"
-    push '"$INSTDIR\_conda.exe" create --dry-run --prefix "$INSTDIR\envs\_virtual_specs_checks" --offline @VIRTUAL_SPECS@ @NO_RCS_ARG@'
-    push 'Failed to check virtual specs: @VIRTUAL_SPECS_DEBUG@'
+    ${Print} "Checking virtual specs compatibility: {{ VIRTUAL_SPECS_DEBUG }}"
+    push '"$INSTDIR\_conda.exe" create --dry-run --prefix "$INSTDIR\envs\_virtual_specs_checks" --offline {{ VIRTUAL_SPECS }} {{ NO_RCS_ARG }}'
+    push 'Failed to check virtual specs: {{ VIRTUAL_SPECS_DEBUG }}'
     push 'WithLog'
     call AbortRetryNSExecWait
     SetDetailsPrint both
     System::Call 'kernel32::SetEnvironmentVariable(t,t)i("CONDA_SOLVER", "").r0'
     ${EndIf}
 
-    @PKG_COMMANDS@
+    {{ PKG_COMMANDS }}
 
     SetDetailsPrint TextOnly
     ${Print} "Setting up the package cache..."
@@ -1301,19 +1275,19 @@ Section "Install"
         call AbortRetryNSExecWait
     NoPreInstall:
 
-    @SETUP_ENVS@
+    {{ SETUP_ENVS }}
 
-    @WRITE_CONDARC@
+    {{ WRITE_CONDARC }}
 
-    AddSize @SIZE@
+    AddSize {{ SIZE }}
 
-#if has_conda is True
+{%- if has_conda %}
     ${Print} "Initializing conda directories..."
     push '"$INSTDIR\pythonw.exe" -E -s "$INSTDIR\Lib\_nsis.py" mkdirs'
     push 'Failed to initialize conda directories'
     push 'WithLog'
     call AbortRetryNSExecWait
-#endif
+{%- endif %}
 
     ${If} $Ana_PostInstall_State = ${BST_CHECKED}
         ${Print} "Running post install..."
@@ -1325,7 +1299,7 @@ Section "Install"
 
     ${If} $Ana_ClearPkgCache_State = ${BST_CHECKED}
         ${Print} "Clearing package cache..."
-        push '"$INSTDIR\_conda.exe" clean --all --force-pkgs-dirs --yes @NO_RCS_ARG@'
+        push '"$INSTDIR\_conda.exe" clean --all --force-pkgs-dirs --yes {{ NO_RCS_ARG }}'
         push 'Failed to clear package cache'
         push 'WithLog'
         call AbortRetryNSExecWait
@@ -1334,7 +1308,7 @@ Section "Install"
     ${If} $Ana_AddToPath_State = ${BST_CHECKED}
         ${Print} "Adding to PATH..."
         push '"$INSTDIR\pythonw.exe" -E -s "$INSTDIR\Lib\_nsis.py" addpath ${PYVERSION} ${NAME} ${VERSION} ${ARCH}'
-        push 'Failed to add @NAME@ to the system PATH'
+        push 'Failed to add {{ NAME }} to the system PATH'
         push 'WithLog'
         call AbortRetryNSExecWait
     ${EndIf}
@@ -1413,7 +1387,7 @@ Section "Uninstall"
 
     # Remove menu items, path entries
     System::Call 'kernel32::SetEnvironmentVariable(t,t)i("CONDA_ROOT_PREFIX", "$INSTDIR")".r0'
-    @UNINSTALL_MENUS@
+    {{ UNINSTALL_MENUS }}
 
     # ensure that MSVC runtime DLLs are on PATH during uninstallation
     ReadEnvStr $0 PATH
@@ -1503,10 +1477,10 @@ Section "Uninstall"
 
 SectionEnd
 
-!if '@SIGNTOOL_COMMAND@' != ''
+!if '{{ SIGNTOOL_COMMAND }}' != ''
     # Signing for installer and uninstaller; nsis 3.08 required for uninstfinalize!
     # "= 0" comparison required to prevent both tasks running in parallel, which would cause signtool to fail
     # %1 is replaced by the installer and uninstaller paths, respectively
-    !finalize '@SIGNTOOL_COMMAND@ "%1"' = 0
-    !uninstfinalize '@SIGNTOOL_COMMAND@ "%1"' = 0
+    !finalize '{{ SIGNTOOL_COMMAND }} "%1"' = 0
+    !uninstfinalize '{{ SIGNTOOL_COMMAND }} "%1"' = 0
 !endif
diff --git a/constructor/osx/check_shortcuts.sh b/constructor/osx/check_shortcuts.sh
index b592b2443..c15adceed 100644
--- a/constructor/osx/check_shortcuts.sh
+++ b/constructor/osx/check_shortcuts.sh
@@ -4,7 +4,7 @@ set -eux
 
 # $2 is the install location, which is ~ by default
 # but which the user can change.
-PREFIX="$2/__NAME_LOWER__"
+PREFIX="$2/{{ pkg_name_lower }}"
 PREFIX=$(cd "$PREFIX"; pwd)
 
 # If the UI selected the "Create shortcuts" option
diff --git a/constructor/osx/checks_before_install.sh b/constructor/osx/checks_before_install.sh
index 54fabc43d..51468c52e 100644
--- a/constructor/osx/checks_before_install.sh
+++ b/constructor/osx/checks_before_install.sh
@@ -9,7 +9,7 @@
 # so the only way to prevent an action is to abort and start again from the beginning.
 set -euo pipefail
 
-PREFIX="$2/__NAME_LOWER__"
+PREFIX="$2/{{ pkg_name_lower }}"
 echo "PREFIX=$PREFIX"
 
 if [[ -e "$PREFIX" ]]; then
diff --git a/constructor/osx/clean_cache.sh b/constructor/osx/clean_cache.sh
index 23c8fc908..d056ce99b 100644
--- a/constructor/osx/clean_cache.sh
+++ b/constructor/osx/clean_cache.sh
@@ -6,6 +6,6 @@
 # but which the user can change.
 set -eux
 
-PREFIX="$2/__NAME_LOWER__"
+PREFIX="$2/{{ pkg_name_lower }}"
 PREFIX=$(cd "$PREFIX"; pwd)
 rm -rf "$PREFIX/pkgs"
diff --git a/constructor/osx/prepare_installation.sh b/constructor/osx/prepare_installation.sh
index d33d3b7af..dd5309ab9 100644
--- a/constructor/osx/prepare_installation.sh
+++ b/constructor/osx/prepare_installation.sh
@@ -8,17 +8,17 @@ set -euo pipefail
 
 notify() {
 # shellcheck disable=SC2050
-if [ "__PROGRESS_NOTIFICATIONS__" = "True" ]; then
+{%- if progress_notifications %}
 osascript <<EOF
-display notification "$1" with title "📦 Install __NAME__ __VERSION__"
+display notification "$1" with title "📦 Install {{ installer_name }} {{ installer_version }}"
 EOF
-fi
+{%- endif %}
 logger -p "install.info" "$1" || echo "$1"
 }
 
 unset DYLD_LIBRARY_PATH
 
-PREFIX="$2/__NAME_LOWER__"
+PREFIX="$2/{{ pkg_name_lower }}"
 PREFIX=$(cd "$PREFIX"; pwd)
 export PREFIX
 echo "PREFIX=$PREFIX"
@@ -38,13 +38,13 @@ touch "$PREFIX/conda-meta/history"
 # micromamba needs an existing pkgs_dir to operate even offline,
 # but we haven't created $PREFIX/pkgs yet... do it in a temporary location
 # shellcheck disable=SC2050
-if [ "__VIRTUAL_SPECS__" != "" ]; then
-    notify "Checking virtual specs compatibility: __VIRTUAL_SPECS__"
-    CONDA_SOLVER="classic" \
-    CONDA_PKGS_DIRS="$(mktemp -d)" \
-    SYSTEM_VERSION_COMPAT=0 \
-    "$CONDA_EXEC" create --dry-run --prefix "$PREFIX/envs/_virtual_specs_checks" --offline __VIRTUAL_SPECS__ __NO_RCS_ARG__
-fi
+{%- if virtual_specs %}
+notify "Checking virtual specs compatibility: {{ virtual_specs }}"
+CONDA_SOLVER="classic" \
+CONDA_PKGS_DIRS="$(mktemp -d)" \
+SYSTEM_VERSION_COMPAT=0 \
+"$CONDA_EXEC" create --dry-run --prefix "$PREFIX/envs/_virtual_specs_checks" --offline {{ virtual_specs }} {{ no_rcs_arg }}
+{%- endif %}
 
 # Create $PREFIX/.nonadmin if the installation didn't require superuser permissions
 if [ "$(id -u)" -ne 0 ]; then
diff --git a/constructor/osx/run_installation.sh b/constructor/osx/run_installation.sh
index ba5aa90d0..708b04a1d 100644
--- a/constructor/osx/run_installation.sh
+++ b/constructor/osx/run_installation.sh
@@ -2,7 +2,7 @@
 # Copyright (c) 2017 Anaconda, Inc.
 # All rights reserved.
 
-# Created by constructor __CONSTRUCTOR_VERSION__
+# Created by constructor {{ constructor_version }}
 
 # COMMON UTILS
 # If you update this block, please propagate changes to the other scripts using it
@@ -10,17 +10,17 @@ set -euo pipefail
 
 notify() {
 # shellcheck disable=SC2050
-if [ "__PROGRESS_NOTIFICATIONS__" = "True" ]; then
+{%- if progress_notifications %}
 osascript <<EOF
 display notification "$1" with title "📦 Install __NAME__ __VERSION__"
 EOF
-fi
+{%- endif %}
 logger -p "install.info" "$1" || echo "$1"
 }
 
 unset DYLD_LIBRARY_PATH
 
-PREFIX="$2/__NAME_LOWER__"
+PREFIX="$2/{{ pkg_name_lower }}"
 PREFIX=$(cd "$PREFIX"; pwd)
 export PREFIX
 echo "PREFIX=$PREFIX"
@@ -29,9 +29,9 @@ CONDA_EXEC="$PREFIX/_conda"
 
 # Check whether the user wants shortcuts or not
 # See check_shortcuts.sh script for details
-ENABLE_SHORTCUTS="__ENABLE_SHORTCUTS__"
+ENABLE_SHORTCUTS="{{ enable_shortcuts }}"
 if [[ -f "$PREFIX/pkgs/user_wants_shortcuts" ]]; then  # this implies ENABLE_SHORTCUTS==true
-    shortcuts="__SHORTCUTS__"
+    shortcuts="{{ shortcuts }}"
 elif [[ "$ENABLE_SHORTCUTS" == "incompatible" ]]; then
     shortcuts=""
 else
@@ -42,13 +42,13 @@ fi
 notify "Installing packages. This might take a few minutes."
 # shellcheck disable=SC2086
 if ! \
-CONDA_REGISTER_ENVS="__REGISTER_ENVS__" \
+CONDA_REGISTER_ENVS="{{ register_envs }}" \
 CONDA_ROOT_PREFIX="$PREFIX" \
 CONDA_SAFETY_CHECKS=disabled \
 CONDA_EXTRA_SAFETY_CHECKS=no \
-CONDA_CHANNELS=__CHANNELS__ \
+CONDA_CHANNELS={{ channels }} \
 CONDA_PKGS_DIRS="$PREFIX/pkgs" \
-"$CONDA_EXEC" install --offline --file "$PREFIX/pkgs/env.txt" -yp "$PREFIX" $shortcuts __NO_RCS_ARG__; then
+"$CONDA_EXEC" install --offline --file "$PREFIX/pkgs/env.txt" -yp "$PREFIX" $shortcuts {{ no_rcs_arg }}; then
     echo "ERROR: could not complete the conda install"
     exit 1
 fi
@@ -75,7 +75,7 @@ for env_pkgs in "${PREFIX}"/pkgs/envs/*/; do
         env_channels="$(cat "${env_pkgs}channels.txt")"
         rm -f "${env_pkgs}channels.txt"
     else
-        env_channels="__CHANNELS__"
+        env_channels="{{ channels }}"
     fi
     if [[ -f "$PREFIX/pkgs/user_wants_shortcuts" ]]; then  # this implies ENABLE_SHORTCUTS==true
         # This file is guaranteed to exist, even if empty
@@ -89,12 +89,12 @@ for env_pkgs in "${PREFIX}"/pkgs/envs/*/; do
 
     # shellcheck disable=SC2086
     CONDA_ROOT_PREFIX="$PREFIX" \
-    CONDA_REGISTER_ENVS="__REGISTER_ENVS__" \
+    CONDA_REGISTER_ENVS="{{ register_envs }}" \
     CONDA_SAFETY_CHECKS=disabled \
     CONDA_EXTRA_SAFETY_CHECKS=no \
     CONDA_CHANNELS="$env_channels" \
     CONDA_PKGS_DIRS="$PREFIX/pkgs" \
-    "$CONDA_EXEC" install --offline --file "${env_pkgs}env.txt" -yp "$PREFIX/envs/$env_name" $env_shortcuts __NO_RCS_ARG__ || exit 1
+    "$CONDA_EXEC" install --offline --file "${env_pkgs}env.txt" -yp "$PREFIX/envs/$env_name" $env_shortcuts {{ no_rcs_arg }} || exit 1
     # Move the prepackaged history file into place
     mv "${env_pkgs}/conda-meta/history" "$PREFIX/envs/$env_name/conda-meta/history"
     rm -f "${env_pkgs}env.txt"
@@ -103,7 +103,7 @@ done
 # Cleanup!
 find "$PREFIX/pkgs" -type d -empty -exec rmdir {} \; 2>/dev/null || :
 
-__WRITE_CONDARC__
+{{ write_condarc }}
 
 if ! "$PREFIX/bin/python" -V; then
     echo "ERROR running Python"
diff --git a/constructor/osx/run_user_script.sh b/constructor/osx/run_user_script.sh
index ca325f9d5..ae3516039 100644
--- a/constructor/osx/run_user_script.sh
+++ b/constructor/osx/run_user_script.sh
@@ -8,17 +8,17 @@ set -euo pipefail
 
 notify() {
 # shellcheck disable=SC2050
-if [ "__PROGRESS_NOTIFICATIONS__" = "True" ]; then
+{%- if progress_notifications %}
 osascript <<EOF
 display notification "$1" with title "📦 Install __NAME__ __VERSION__"
 EOF
-fi
+{%- endif %}
 logger -p "install.info" "$1" || echo "$1"
 }
 
 unset DYLD_LIBRARY_PATH
 
-PREFIX="$2/__NAME_LOWER__"
+PREFIX="$2/{{ pkg_name_lower }}"
 PREFIX=$(cd "$PREFIX"; pwd)
 export PREFIX
 echo "PREFIX=$PREFIX"
@@ -26,13 +26,13 @@ CONDA_EXEC="$PREFIX/_conda"
 # /COMMON UTILS
 
 # Expose these to user scripts as well
-export INSTALLER_NAME="__NAME__"
-export INSTALLER_VER="__VERSION__"
-export INSTALLER_PLAT="__PLAT__"
+export INSTALLER_NAME="{{ installer_name }}"
+export INSTALLER_VER="{{ installer_version }}"
+export INSTALLER_PLAT="{{ installer_platform }}"
 export INSTALLER_TYPE="PKG"
 export INSTALLER_UNATTENDED="?"
-export PRE_OR_POST="__PRE_OR_POST__"
-_SCRIPT_ENV_VARIABLES_=''  # Templated extra environment variable(s)
+export PRE_OR_POST="{{ pre_or_post }}"
+{{ script_env_variables }}
 
 # Run user-provided script
 if [ -f "$PREFIX/pkgs/user_${PRE_OR_POST}" ]; then
diff --git a/constructor/osx/update_path.sh b/constructor/osx/update_path.sh
index ec61d8cea..cf79ce964 100644
--- a/constructor/osx/update_path.sh
+++ b/constructor/osx/update_path.sh
@@ -6,7 +6,7 @@
 # change.
 set -eux
 
-PREFIX="$2/__NAME_LOWER__"
+PREFIX="$2/{{ pkg_name_lower }}"
 PREFIX=$(cd "$PREFIX"; pwd)
 INIT_FILES=$("$PREFIX/bin/python" -m conda init --all | tee)
 
diff --git a/constructor/osxpkg.py b/constructor/osxpkg.py
index 22444472c..b3831ec7f 100644
--- a/constructor/osxpkg.py
+++ b/constructor/osxpkg.py
@@ -15,15 +15,14 @@
 from .conda_interface import conda_context
 from .construct import ns_platform, parse
 from .imaging import write_images
+from .jinja import render_template
 from .signing import CodeSign
 from .utils import (
     add_condarc,
     approx_size_kb,
     explained_check_call,
-    fill_template,
     get_final_channels,
     parse_virtual_specs,
-    preprocess,
     rm_rf,
     shortcuts_flags,
 )
@@ -318,8 +317,8 @@ def move_script(src, dst, info, ensure_shebang=False, user_script_type=None):
         data = fi.read()
 
     # ppd hosts the conditions for the #if/#else/#endif preprocessors on scripts
-    ppd = ns_platform(info['_platform'])
-    ppd['check_path_spaces'] = bool(info.get("check_path_spaces", True))
+    variables = ns_platform(info['_platform'])
+    variables['check_path_spaces'] = bool(info.get("check_path_spaces", True))
 
     # This is necessary for when installing on case-sensitive macOS filesystems.
     pkg_name_lower = info.get("pkg_name", info['name']).lower()
@@ -332,29 +331,25 @@ def move_script(src, dst, info, ensure_shebang=False, user_script_type=None):
     ).format(CHOSEN_PATH=f"$2/{pkg_name_lower}")
     # __osx is tested by the PKG metadata directly, no need to repeat
     virtual_specs = [spec for spec in info.get("virtual_specs", ()) if "__osx" not in spec]
-    replace = {
-        'NAME': info['name'],
-        'NAME_LOWER': pkg_name_lower,
-        'VERSION': info['version'],
-        'PLAT': info['_platform'],
-        'CHANNELS': ','.join(get_final_channels(info)),
-        'WRITE_CONDARC': '\n'.join(add_condarc(info)),
-        'PATH_EXISTS_ERROR_TEXT': path_exists_error_text,
-        'PROGRESS_NOTIFICATIONS': str(info.get('progress_notifications', False)),
-        'PRE_OR_POST': user_script_type or '__PRE_OR_POST__',
-        'CONSTRUCTOR_VERSION': info['CONSTRUCTOR_VERSION'],
-        'SHORTCUTS': shortcuts_flags(info),
-        'ENABLE_SHORTCUTS': str(info['_enable_shortcuts']).lower(),
-        'REGISTER_ENVS': str(info.get("register_envs", True)).lower(),
-        'VIRTUAL_SPECS': shlex.join(virtual_specs),
-        'NO_RCS_ARG': info.get('_ignore_condarcs_arg', ''),
-    }
-    data = preprocess(data, ppd)
-    custom_variables = info.get('script_env_variables', {})
-    data = fill_template(data, replace)
-
-    data = data.replace("_SCRIPT_ENV_VARIABLES_=''", '\n'.join(
-        [f"export {key}='{value}'" for key, value in custom_variables.items()]))
+    variables["pkg_name_lower"] = pkg_name_lower
+    variables["installer_name"] = info['name']
+    variables["installer_version"] = info['version']
+    variables["installer_platform"] = info['_platform']
+    variables["channels"] = ','.join(get_final_channels(info))
+    variables["write_condarc"] = '\n'.join(add_condarc(info))
+    variables["path_exists_error_text"] = path_exists_error_text
+    variables["progress_notifications"] = info.get('progress_notifications', False)
+    variables["pre_or_post"] = user_script_type or '__PRE_OR_POST__'
+    variables["constructor_version"] = info['CONSTRUCTOR_VERSION']
+    variables["shortcuts"] = shortcuts_flags(info)
+    variables["enable_shortcuts"] = str(info['_enable_shortcuts']).lower()
+    variables["register_envs"] = str(info.get("register_envs", True)).lower()
+    variables["virtual_specs"] = shlex.join(virtual_specs)
+    variables["no_rcs_arg"] = info.get('_ignore_condarcs_arg', '')
+    variables["script_env_variables"] = '\n'.join(
+        [f"export {key}='{value}'" for key, value in info.get('script_env_variables', {}).items()])
+
+    data = render_template(data, **variables)
 
     with open(dst, 'w') as fo:
         if (
diff --git a/constructor/shar.py b/constructor/shar.py
index e048fafb9..aa5988435 100644
--- a/constructor/shar.py
+++ b/constructor/shar.py
@@ -14,6 +14,7 @@
 from os.path import basename, dirname, getsize, isdir, join, relpath
 
 from .construct import ns_platform
+from .jinja import render_template
 from .preconda import copy_extra_files
 from .preconda import files as preconda_files
 from .preconda import write_files as preconda_write_files
@@ -21,11 +22,9 @@
     add_condarc,
     approx_size_kb,
     filename_dist,
-    fill_template,
     get_final_channels,
     hash_files,
     parse_virtual_specs,
-    preprocess,
     read_ascii_only,
     shortcuts_flags,
 )
@@ -56,24 +55,24 @@ def get_header(conda_exec, tarball, info):
     name = info['name']
 
     has_license = bool(info.get('license_file'))
-    ppd = ns_platform(info['_platform'])
-    ppd['keep_pkgs'] = bool(info.get('keep_pkgs', False))
-    ppd['batch_mode'] = bool(info.get('batch_mode', False))
-    ppd['has_license'] = has_license
-    if ppd['batch_mode'] and has_license:
+    variables = ns_platform(info['_platform'])
+    variables['keep_pkgs'] = bool(info.get('keep_pkgs', False))
+    variables['batch_mode'] = bool(info.get('batch_mode', False))
+    variables['has_license'] = has_license
+    if variables['batch_mode'] and has_license:
         raise Exception(
             "It is not possible to use both the 'batch_mode' and "
             "'license_file' options together."
         )
     for key in 'pre_install', 'post_install', 'pre_uninstall':
-        ppd['has_%s' % key] = bool(key in info)
+        variables['has_%s' % key] = bool(key in info)
         if key in info:
-            ppd['direct_execute_%s' % key] = has_shebang(info[key])
-    ppd['initialize_conda'] = info.get('initialize_conda', True)
-    ppd['initialize_by_default'] = info.get('initialize_by_default', False)
-    ppd['has_conda'] = info['_has_conda']
-    ppd['enable_shortcuts'] = str(info['_enable_shortcuts']).lower()
-    ppd['check_path_spaces'] = info.get("check_path_spaces", True)
+            variables['direct_execute_%s' % key] = has_shebang(info[key])
+    variables['initialize_conda'] = info.get('initialize_conda', True)
+    variables['initialize_by_default'] = info.get('initialize_by_default', False)
+    variables['has_conda'] = info['_has_conda']
+    variables['enable_shortcuts'] = str(info['_enable_shortcuts']).lower()
+    variables['check_path_spaces'] = info.get("check_path_spaces", True)
     install_lines = list(add_condarc(info))
     # Omit __osx and __glibc because those are tested with shell code direcly
     virtual_specs = [
@@ -81,45 +80,35 @@ def get_header(conda_exec, tarball, info):
         for spec in info.get("virtual_specs", ())
         if "__osx" not in spec and "__glibc" not in spec
     ]
-    # Needs to happen first -- can be templated
-    replace = {
-        'CONSTRUCTOR_VERSION': info['CONSTRUCTOR_VERSION'],
-        'NAME': name,
-        'name': name.lower(),
-        'VERSION': info['version'],
-        'PLAT': info['_platform'],
-        'DEFAULT_PREFIX': info.get('default_prefix',
-                                   '${HOME:-/opt}/%s' % name.lower()),
-        'MD5': hash_files([conda_exec, tarball]),
-        'FIRST_PAYLOAD_SIZE': str(getsize(conda_exec)),
-        'SECOND_PAYLOAD_SIZE': str(getsize(tarball)),
-        'INSTALL_COMMANDS': '\n'.join(install_lines),
-        'CHANNELS': ','.join(get_final_channels(info)),
-        'CONCLUSION_TEXT': info.get("conclusion_text", "installation finished."),
-        'pycache': '__pycache__',
-        'SHORTCUTS': shortcuts_flags(info),
-        'REGISTER_ENVS': str(info.get("register_envs", True)).lower(),
-        'TOTAL_INSTALLATION_SIZE_KB': str(approx_size_kb(info, "total")),
-        'VIRTUAL_SPECS': shlex.join(virtual_specs),
-        'NO_RCS_ARG': info.get('_ignore_condarcs_arg', ''),
-    }
+    variables['installer_name'] = name
+    variables['installer_version'] = info['version']
+    variables['installer_platform'] = info['_platform']
+    variables['installer_md5'] = hash_files([conda_exec, tarball])
+    variables['default_prefix'] = info.get('default_prefix', '${HOME:-/opt}/%s' % name.lower())
+    variables['first_payload_size'] = getsize(conda_exec)
+    variables['second_payload_size'] = getsize(tarball)
+    variables['install_commands'] = '\n'.join(install_lines)
+    variables['channels'] = ','.join(get_final_channels(info))
+    variables['conclusion_text'] = info.get("conclusion_text", "installation finished.")
+    variables['pycache'] = '__pycache__'
+    variables['shortcuts'] = shortcuts_flags(info)
+    variables['register_envs'] = str(info.get("register_envs", True)).lower()
+    variables['total_installation_size_kb'] = str(approx_size_kb(info, "total"))
+    variables['virtual_specs'] = shlex.join(virtual_specs)
+    variables['no_rcs_arg'] = info.get('_ignore_condarcs_arg', '')
     if has_license:
-        replace['LICENSE'] = read_ascii_only(info['license_file'])
+        variables['license'] = read_ascii_only(info['license_file'])
 
     virtual_specs = parse_virtual_specs(info)
     min_osx_version = virtual_specs.get("__osx", {}).get("min") or ""
-    replace['MIN_OSX_VERSION'] = ppd['min_osx_version'] = min_osx_version
+    variables['min_osx_version'] = min_osx_version
     min_glibc_version = virtual_specs.get("__glibc", {}).get("min") or ""
-    replace['MIN_GLIBC_VERSION'] = ppd['min_glibc_version'] = min_glibc_version
+    variables['min_glibc_version'] = min_glibc_version
 
-    data = read_header_template()
-    data = preprocess(data, ppd)
-    custom_variables = info.get('script_env_variables', {})
-    data = fill_template(data, replace)
+    variables['script_env_variables'] = '\n'.join(
+        [f"export {key}='{value}'" for key, value in info.get('script_env_variables', {}).items()])
 
-    data = data.replace("_SCRIPT_ENV_VARIABLES_=''", '\n'.join(
-        [f"export {key}='{value}'" for key, value in custom_variables.items()]))
-    return data
+    return render_template(read_header_template(), **variables)
 
 
 def create(info, verbose=False):
diff --git a/constructor/utils.py b/constructor/utils.py
index dc44f838e..730ea47e3 100644
--- a/constructor/utils.py
+++ b/constructor/utils.py
@@ -9,6 +9,7 @@
 import math
 import re
 import sys
+import warnings
 from io import StringIO
 from os import environ, sep, unlink
 from os.path import isdir, isfile, islink, join, normpath
@@ -53,6 +54,10 @@ def yaml_to_string(data):
 
 
 def fill_template(data, d, exceptions=[]):
+    warnings.warn(
+        "This function is deprecated and will be removed. Use '.jinja.render_template' instead.",
+        DeprecationWarning,
+    )
     pat = re.compile(r'__(\w+)__')
 
     def replace(match):
@@ -105,6 +110,10 @@ def read_ascii_only(path):
 
 
 def preprocess(data, namespace):
+    warnings.warn(
+        "This function is deprecated and will be removed. Use '.jinja.render_template' instead.",
+        DeprecationWarning,
+    )
 
     def if_repl(match):
         cond = match.group(1).strip()
diff --git a/constructor/winexe.py b/constructor/winexe.py
index 7f8c9968d..16d42304c 100644
--- a/constructor/winexe.py
+++ b/constructor/winexe.py
@@ -16,6 +16,7 @@
 
 from .construct import ns_platform
 from .imaging import write_images
+from .jinja import render_template
 from .preconda import copy_extra_files
 from .preconda import write_files as preconda_write_files
 from .signing import AzureSignTool, WindowsSignTool
@@ -23,10 +24,8 @@
     add_condarc,
     approx_size_kb,
     filename_dist,
-    fill_template,
     get_final_channels,
     make_VIProductVersion,
-    preprocess,
     shortcuts_flags,
     win_str_esc,
 )
@@ -242,70 +241,52 @@ def make_nsi(
     info['pre_install_desc'] = info.get('pre_install_desc', "")
     info['post_install_desc'] = info.get('post_install_desc', "")
 
-    replace = {
-        'NAME': name,
-        'VERSION': info['version'],
-        'COMPANY': info.get('company', 'Unknown, Inc.'),
-        'PLATFORM': info['_platform'],
-        'ARCH': '%d-bit' % arch,
-        'PY_VER': ".".join(py_version.split(".")[:2]),
-        'PYVERSION_JUSTDIGITS': ''.join(py_version.split('.')),
-        'PYVERSION': py_version,
-        'PYVERSION_MAJOR': py_version.split('.')[0],
-        'DEFAULT_PREFIX': info.get('default_prefix', join('%USERPROFILE%', name.lower())),
-        'DEFAULT_PREFIX_DOMAIN_USER': info.get('default_prefix_domain_user',
+    variables = {
+        'installer_name': name,
+        'installer_version': info['version'],
+        'company': info.get('company', 'Unknown, Inc.'),
+        'installer_platform': info['_platform'],
+        'arch': '%d-bit' % arch,
+        'py_ver': ".".join(py_version.split(".")[:2]),
+        'pyversion_justdigits': ''.join(py_version.split('.')),
+        'pyversion': py_version,
+        'pyversion_major': py_version.split('.')[0],
+        'default_prefix': info.get('default_prefix', join('%USERPROFILE%', name.lower())),
+        'default_prefix_domain_user': info.get('default_prefix_domain_user',
                                                join('%LOCALAPPDATA%', name.lower())),
-        'DEFAULT_PREFIX_ALL_USERS': info.get('default_prefix_all_users',
+        'default_prefix_all_users': info.get('default_prefix_all_users',
                                              join('%ALLUSERSPROFILE%', name.lower())),
-        'PRE_INSTALL_DESC': info['pre_install_desc'],
-        'POST_INSTALL_DESC': info['post_install_desc'],
-        'ENABLE_SHORTCUTS': "yes" if info['_enable_shortcuts'] is True else "no",
-        'SHOW_REGISTER_PYTHON': "yes" if info.get("register_python", True) else "no",
-        'SHOW_ADD_TO_PATH': "yes" if info.get("initialize_conda", True) else "no",
-        'OUTFILE': info['_outpath'],
-        'VIPV': make_VIProductVersion(info['version']),
-        'CONSTRUCTOR_VERSION': info['CONSTRUCTOR_VERSION'],
-        'ICONFILE': '@icon.ico',
-        'HEADERIMAGE': '@header.bmp',
-        'WELCOMEIMAGE': '@welcome.bmp',
-        'LICENSEFILE': abspath(info.get('license_file', join(NSIS_DIR, 'placeholder_license.txt'))),
-        'CONDA_HISTORY': '@' + join('conda-meta', 'history'),
-        'CONDA_EXE': '@_conda.exe',
-        'ENV_TXT': '@env.txt',
-        'URLS_FILE': '@urls',
-        'URLS_TXT_FILE': '@urls.txt',
-        'PRE_INSTALL': '@pre_install.bat',
-        'POST_INSTALL': '@post_install.bat',
-        'PRE_UNINSTALL': '@pre_uninstall.bat',
-        'INDEX_CACHE': '@cache',
-        'REPODATA_RECORD': '@repodata_record.json',
+        'pre_install_desc': info['pre_install_desc'],
+        'post_install_desc': info['post_install_desc'],
+        'enable_shortcuts': "yes" if info['_enable_shortcuts'] is True else "no",
+        'show_register_python': "yes" if info.get("register_python", True) else "no",
+        'show_add_to_path': "yes" if info.get("initialize_conda", True) else "no",
+        'outfile': info['_outpath'],
+        'vipv': make_VIProductVersion(info['version']),
+        'constructor_version': info['CONSTRUCTOR_VERSION'],
+        'iconfile': '@icon.ico',
+        'headerimage': '@header.bmp',
+        'welcomeimage': '@welcome.bmp',
+        'licensefile': abspath(info.get('license_file', join(NSIS_DIR, 'placeholder_license.txt'))),
+        'conda_history': '@' + join('conda-meta', 'history'),
+        'conda_exe': '@_conda.exe',
+        'env_txt': '@env.txt',
+        'urls_file': '@urls',
+        'urls_txt_file': '@urls.txt',
+        'pre_install': '@pre_install.bat',
+        'post_install': '@post_install.bat',
+        'pre_uninstall': '@pre_uninstall.bat',
+        'index_cache': '@cache',
+        'repodata_record': '@repodata_record.json',
     }
 
-    # These are NSIS predefines and must not be replaced
-    # https://nsis.sourceforge.io/Docs/Chapter5.html#precounter
-    nsis_predefines = [
-        "COUNTER",
-        "DATE",
-        "FILE",
-        "FILEDIR",
-        "FUNCTION",
-        "GLOBAL",
-        "LINE",
-        "MACRO",
-        "PAGEEX",
-        "SECTION",
-        "TIME",
-        "TIMESTAMP",
-        "UNINSTALL",
-    ]
-
     conclusion_text = info.get("conclusion_text", "")
     if conclusion_text:
         conclusion_lines = conclusion_text.strip().splitlines()
-        replace['CONCLUSION_TITLE'] = conclusion_lines[0].strip()
+        variables['conclusion_title'] = conclusion_lines[0].strip()
         # See https://nsis.sourceforge.io/Docs/Modern%20UI/Readme.html#toggle_pgf
         # for the newlines business
-        replace['CONCLUSION_TEXT'] = "\r\n".join(conclusion_lines[1:])
+        variables['conclusion_text'] = "\r\n".join(conclusion_lines[1:])
 
     for key in ['welcome_file', 'conclusion_file', 'post_install_pages']:
         value = info.get(key, "")
@@ -330,32 +311,71 @@ def make_nsi(
                     )
                 info[key] = valid_values
 
-    for key, value in replace.items():
+    for key, value in variables.items():
         if value.startswith('@'):
             value = join(dir_path, value[1:])
-        replace[key] = win_str_esc(value)
-
-    data = read_nsi_tmpl(info)
-    ppd = ns_platform(info['_platform'])
-    ppd['initialize_conda'] = info.get('initialize_conda', True)
-    ppd['initialize_by_default'] = info.get('initialize_by_default', None)
-    ppd['register_python'] = info.get('register_python', True)
-    ppd['register_python_default'] = info.get('register_python_default', None)
-    ppd['check_path_length'] = info.get('check_path_length', None)
-    ppd['check_path_spaces'] = info.get('check_path_spaces', True)
-    ppd['keep_pkgs'] = info.get('keep_pkgs') or False
-    ppd['pre_install_exists'] = bool(info.get('pre_install'))
-    ppd['post_install_exists'] = bool(info.get('post_install'))
-    ppd['with_conclusion_text'] = bool(conclusion_text)
-    ppd["enable_debugging"] = bool(os.environ.get("NSIS_USING_LOG_BUILD"))
-    ppd["has_conda"] = info["_has_conda"]
-    ppd["custom_welcome"] = info.get("welcome_file", "").endswith(".nsi")
-    ppd["custom_conclusion"] = info.get("conclusion_file", "").endswith(".nsi")
-    ppd["has_license"] = bool(info.get("license_file"))
-    ppd["post_install_pages"] = bool(info.get("post_install_pages"))
-
-    data = preprocess(data, ppd)
-    data = fill_template(data, replace, exceptions=nsis_predefines)
+        variables[key] = win_str_esc(value)
+
+    # From now on, the items added to variables will NOT be escaped
+
+    # These are mostly booleans we use with if-checks
+    variables.update(ns_platform(info['_platform']))
+    variables['initialize_conda'] = info.get('initialize_conda', True)
+    variables['initialize_by_default'] = info.get('initialize_by_default', None)
+    variables['register_python'] = info.get('register_python', True)
+    variables['register_python_default'] = info.get('register_python_default', None)
+    variables['check_path_length'] = info.get('check_path_length', None)
+    variables['check_path_spaces'] = info.get('check_path_spaces', True)
+    variables['keep_pkgs'] = info.get('keep_pkgs') or False
+    variables['pre_install_exists'] = bool(info.get('pre_install'))
+    variables['post_install_exists'] = bool(info.get('post_install'))
+    variables['with_conclusion_text'] = bool(conclusion_text)
+    variables["enable_debugging"] = bool(os.environ.get("NSIS_USING_LOG_BUILD"))
+    variables["has_conda"] = info["_has_conda"]
+    variables["custom_welcome"] = info.get("welcome_file", "").endswith(".nsi")
+    variables["custom_conclusion"] = info.get("conclusion_file", "").endswith(".nsi")
+    variables["has_license"] = bool(info.get("license_file"))
+    variables["post_install_pages"] = bool(info.get("post_install_pages"))
+
+    approx_pkgs_size_kb = approx_size_kb(info, "pkgs")
+
+    # UPPERCASE variables are unescaped (and unquoted)
+    variables['NAME'] = name
+    variables['NSIS_DIR'] = NSIS_DIR
+    variables['BITS'] = str(arch)
+    variables['PKG_COMMANDS'] = '\n    '.join(pkg_commands(download_dir, dists))
+    variables['SIGNTOOL_COMMAND'] = signing_tool.get_signing_command() if signing_tool else ""
+    variables['SETUP_ENVS'] = '\n    '.join(setup_envs_commands(info, dir_path))
+    variables['WRITE_CONDARC'] = '\n    '.join(add_condarc(info))
+    variables['SIZE'] = approx_pkgs_size_kb
+    variables['UNINSTALL_NAME'] = info.get(
+        'uninstall_name',
+        '${NAME} ${VERSION} (Python ${PYVERSION} ${ARCH})'
+    )
+    variables['UNINSTALL_MENUS'] = '\n    '.join(uninstall_menus_commands(info))
+    variables['EXTRA_FILES'] = '\n    '.join(extra_files_commands(extra_files, dir_path))
+    variables['SCRIPT_ENV_VARIABLES'] = '\n    '.join(setup_script_env_variables(info))
+    variables['CUSTOM_WELCOME_FILE'] = (
+        custom_nsi_insert_from_file(info.get('welcome_file', ''))
+        if variables['custom_welcome']
+        else ''
+    )
+    variables['CUSTOM_CONCLUSION_FILE'] = (
+        custom_nsi_insert_from_file(info.get('conclusion_file', ''))
+        if variables['custom_conclusion']
+        else ''
+    )
+    variables['POST_INSTALL_PAGES'] = '\n'.join(
+        custom_nsi_insert_from_file(file) for file in info.get('post_install_pages', [])
+    )
+    variables['TEMP_EXTRA_FILES'] = '\n    '.join(insert_tempfiles_commands(temp_extra_files))
+    variables['VIRTUAL_SPECS'] = " ".join([f'"{spec}"' for spec in info.get("virtual_specs", ())])
+    # This is the same but without quotes so we can print it fine
+    variables['VIRTUAL_SPECS_DEBUG'] = " ".join([spec for spec in info.get("virtual_specs", ())])
+    variables['LICENSEFILENAME'] = basename(info.get('license_file', 'placeholder_license.txt'))
+    variables['NO_RCS_ARG'] = info.get('_ignore_condarcs_arg', '')
+
+    data = render_template(read_nsi_tmpl(info), **variables)
     if info['_platform'].startswith("win") and sys.platform != 'win32':
         # Branding /TRIM commannd is unsupported on non win platform
         data_lines = data.split("\n")
@@ -365,51 +385,6 @@ def make_nsi(
                 break
         data = "\n".join(data_lines)
 
-    approx_pkgs_size_kb = approx_size_kb(info, "pkgs")
-
-    # these are unescaped (and unquoted)
-    for key, value in [
-        ('@NAME@', name),
-        ('@NSIS_DIR@', NSIS_DIR),
-        ('@BITS@', str(arch)),
-        ('@PKG_COMMANDS@', '\n    '.join(pkg_commands(download_dir, dists))),
-        ('@SIGNTOOL_COMMAND@', signing_tool.get_signing_command() if signing_tool else ""),
-        ('@SETUP_ENVS@', '\n    '.join(setup_envs_commands(info, dir_path))),
-        ('@WRITE_CONDARC@', '\n    '.join(add_condarc(info))),
-        ('@SIZE@', str(approx_pkgs_size_kb)),
-        ('@UNINSTALL_NAME@', info.get('uninstall_name',
-                                      '${NAME} ${VERSION} (Python ${PYVERSION} ${ARCH})'
-                                      )),
-        ('@UNINSTALL_MENUS@', '\n    '.join(uninstall_menus_commands(info))),
-        ('@EXTRA_FILES@', '\n    '.join(extra_files_commands(extra_files, dir_path))),
-        ('@SCRIPT_ENV_VARIABLES@', '\n    '.join(setup_script_env_variables(info))),
-        (
-            '@CUSTOM_WELCOME_FILE@',
-            custom_nsi_insert_from_file(info.get('welcome_file', ''))
-            if ppd['custom_welcome']
-            else ''
-        ),
-        (
-            '@CUSTOM_CONCLUSION_FILE@',
-            custom_nsi_insert_from_file(info.get('conclusion_file', ''))
-            if ppd['custom_conclusion']
-            else ''
-        ),
-        (
-            '@POST_INSTALL_PAGES@',
-            '\n'.join(
-                custom_nsi_insert_from_file(file) for file in info.get('post_install_pages', [])
-            ),
-        ),
-        ('@TEMP_EXTRA_FILES@', '\n    '.join(insert_tempfiles_commands(temp_extra_files))),
-        ('@VIRTUAL_SPECS@', " ".join([f'"{spec}"' for spec in info.get("virtual_specs", ())])),
-        # This is the same but without quotes so we can print it fine
-        ('@VIRTUAL_SPECS_DEBUG@', " ".join([spec for spec in info.get("virtual_specs", ())])),
-        ('@LICENSEFILENAME@', basename(info.get('license_file', 'placeholder_license.txt'))),
-        ('@NO_RCS_ARG@', info.get('_ignore_condarcs_arg', '')),
-    ]:
-        data = data.replace(key, value)
-
     nsi_path = join(dir_path, 'main.nsi')
     with open(nsi_path, 'w') as fo:
         fo.write(data)
diff --git a/dev/environment.yml b/dev/environment.yml
index 50a2b25d1..721e3419c 100644
--- a/dev/environment.yml
+++ b/dev/environment.yml
@@ -7,3 +7,4 @@ dependencies:
   - ruamel.yaml >=0.11.14,<0.19
   - conda-standalone # >=23.11.0
   - pillow >=3.1  # [osx or win]
+  - jinja2
diff --git a/news/892-jinja b/news/892-jinja
new file mode 100644
index 000000000..ea494c598
--- /dev/null
+++ b/news/892-jinja
@@ -0,0 +1,19 @@
+### Enhancements
+
+* Use Jinja for templating logic. (#892)
+
+### Bug fixes
+
+* <news item>
+
+### Deprecations
+
+* `constructor.utils.preprocess` and `constructor.utils.fill_template` are deprecated. (#892)
+
+### Docs
+
+* <news item>
+
+### Other
+
+* <news item>
diff --git a/pyproject.toml b/pyproject.toml
index f1bb954a9..6c80b2811 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -15,6 +15,7 @@ dependencies = [
     "conda >=4.6",
     "ruamel.yaml >=0.11.14,<0.19",
     "pillow >=3.1 ; platform_system=='Windows' or platform_system=='Darwin'",
+    "jinja2",
 ]
 
 [project.scripts]
diff --git a/recipe/meta.yaml b/recipe/meta.yaml
index 4158f0dbf..e89e93a27 100644
--- a/recipe/meta.yaml
+++ b/recipe/meta.yaml
@@ -23,6 +23,7 @@ requirements:
     - python  # >=3.8
     - ruamel.yaml >=0.11.14,<0.19
     - conda-standalone
+    - jinja2
     - pillow >=3.1     # [win or osx]
     - nsis >=3.08      # [win]
   run_constrained:     # [unix]
diff --git a/tests/test_header.py b/tests/test_header.py
index 539d01e0a..8e452387f 100644
--- a/tests/test_header.py
+++ b/tests/test_header.py
@@ -1,4 +1,3 @@
-import itertools
 import subprocess
 import sys
 import tempfile
@@ -13,8 +12,9 @@
 else:
     # Tests with OSX_DIR are skipped, but a placeholder is needed for pytest
     OSX_DIR = ""
+from constructor import __version__
+from constructor.jinja import render_template
 from constructor.shar import read_header_template
-from constructor.utils import preprocess
 
 
 @lru_cache
@@ -39,90 +39,6 @@ def run_shellcheck(script):
     return findings, p.returncode
 
 
-def test_linux_template_processing():
-    template = read_header_template()
-    errors = []
-    for (
-        osx,
-        direct_execute_post_install,
-        direct_execute_pre_install,
-        batch_mode,
-        keep_pkgs,
-        has_conda,
-        has_license,
-        initialize_conda,
-        initialize_by_default,
-        has_post_install,
-        has_pre_install,
-        enable_shortcuts,
-        check_path_spaces,
-        arch,
-        min_glibc_version,
-        min_osx_version,
-    ) in itertools.product(
-        [False, True],
-        [False, True],
-        [False, True],
-        [False, True],
-        [False, True],
-        [False, True],
-        [False, True],
-        [False, True],
-        [False, True],
-        [False, True],
-        [False, True],
-        [False, True],
-        [False, True],
-        ["x86", "x86_64", " ppc64le", "s390x", "aarch64"],
-        [None, "2.17"],
-        [None, "10.13"],
-    ):
-        params = {
-            "has_license": has_license,
-            "osx": osx,
-            "batch_mode": batch_mode,
-            "keep_pkgs": keep_pkgs,
-            "has_conda": has_conda,
-            "x86": arch == "x86",
-            "x86_64": arch == "x86_64",
-            "ppc64le": arch == "ppc64le",
-            "s390x": arch == "s390x",
-            "aarch64": arch == "aarch64",
-            "linux": not osx,
-            "has_pre_install": has_pre_install,
-            "direct_execute_pre_install": direct_execute_pre_install,
-            "has_post_install": has_post_install,
-            "direct_execute_post_install": direct_execute_post_install,
-            "initialize_conda": initialize_conda,
-            "initialize_by_default": initialize_by_default,
-            "enable_shortcuts": enable_shortcuts,
-            "check_path_spaces": check_path_spaces,
-            "min_glibc_version": min_glibc_version,
-            "min_osx_version": min_osx_version,
-        }
-        processed = preprocess(template, params)
-        for template_string in ["#if", "#else", "#endif"]:
-            if template_string in processed:
-                errors.append(
-                    f"Found '{template_string}' after processing header.sh with '{params}'."
-                )
-
-    assert not errors
-
-
-@pytest.mark.skipif(sys.platform != "darwin", reason="Only on MacOS")
-@pytest.mark.parametrize("arch", ["x86_64", "arm64"])
-@pytest.mark.parametrize("check_path_spaces", [False, True])
-@pytest.mark.parametrize("script", sorted(Path(OSX_DIR).glob("*.sh")))
-def test_osxpkg_scripts_template_processing(arch, check_path_spaces, script):
-    with script.open() as f:
-        data = f.read()
-    processed = preprocess(data, {"arch": arch, "check_path_spaces": check_path_spaces})
-    assert "#if" not in processed
-    assert "#else" not in processed
-    assert "#endif" not in processed
-
-
 @pytest.mark.skipif(sys.platform != "darwin", reason="Only on MacOS")
 @pytest.mark.skipif(available_command("shellcheck") is False, reason="requires shellcheck")
 @pytest.mark.parametrize("arch", ["x86_64", "arm64"])
@@ -133,12 +49,26 @@ def test_osxpkg_scripts_template_processing(arch, check_path_spaces, script):
 def test_osxpkg_scripts_shellcheck(arch, check_path_spaces, script):
     with script.open() as f:
         data = f.read()
-    processed = preprocess(
+    processed = render_template(
         data,
-        {
-            "arch": arch,
-            "check_path_spaces": check_path_spaces,
-        },
+        arch=arch,
+        check_path_spaces=check_path_spaces,
+        pkg_name_lower="example",
+        installer_name="Example",
+        installer_version="1.2.3",
+        installer_platform="osx-64",
+        channels="conda-forge",
+        write_condarc="",
+        path_exists_error_text="Error",
+        progress_notifications=True,
+        pre_or_post="pre",
+        constructor_version=__version__,
+        shortcuts="",
+        enable_shortcuts=True,
+        register_envs=True,
+        virtual_specs="__osx>=10.13",
+        no_rcs_arg="",
+        script_env_variables="",
     )
 
     findings, returncode = run_shellcheck(processed)
@@ -183,9 +113,9 @@ def test_template_shellcheck(
     min_osx_version,
 ):
     template = read_header_template()
-    processed = preprocess(
+    processed = render_template(
         template,
-        {
+        **{
             "has_license": has_license,
             "osx": osx,
             "batch_mode": batch_mode,
@@ -207,6 +137,24 @@ def test_template_shellcheck(
             "enable_shortcuts": enable_shortcuts,
             "min_glibc_version": min_glibc_version,
             "min_osx_version": min_osx_version,
+            "first_payload_size": "1024",
+            "second_payload_size": "512",
+            "constructor_version": __version__,
+            "installer_name": "Example",
+            "installer_version": "1.2.3",
+            "installer_platform": "linux-64",
+            "installer_md5": "a0098a2c837f4cf50180cfc0a041b2af",
+            "script_env_variables": "",  # TODO: Fill this in with actual value
+            "default_prefix": "/opt/Example",
+            "license": "Some text",
+            "total_installation_size_kb": "1024",
+            "virtual_specs": "__glibc>=2.17",
+            "shortcuts": "",
+            "register_envs": "1",
+            "channels": "conda-forge",
+            "no_rcs_arg": "",
+            "install_commands": "",  # TODO: Fill this in with actual value
+            "conclusion_text": "Something",
         },
     )
 
diff --git a/tests/test_utils.py b/tests/test_utils.py
index b66d11738..fc3f9fc50 100644
--- a/tests/test_utils.py
+++ b/tests/test_utils.py
@@ -1,6 +1,6 @@
 from os import sep
 
-from constructor.utils import fill_template, make_VIProductVersion, normalize_path, preprocess
+from constructor.utils import make_VIProductVersion, normalize_path
 
 
 def test_make_VIProductVersion():
@@ -14,72 +14,9 @@ def test_make_VIProductVersion():
     assert f('x') == '0.0.0.0'
 
 
-def test_fill_template():
-    template = """\
-My name is __NAME__!
-I am __AGE__ years old.
-Sincerely __NAME__
-"""
-    res = """\
-My name is Hugo!
-I am 44 years old.
-Sincerely Hugo
-"""
-    info = {'NAME': 'Hugo', 'AGE': '44', 'SEX': 'male'}
-    assert fill_template(template, info) == res
-
-
-def test_preprocess():
-    code = """\
-A
-#if True
-  always True
-  another line
-#endif
-B
-#if False
-  never see this
-#endif
-C
-#if x == 0
-  x = 0
-#else
-  x != 0
-#endif
-D
-#if x != 0
-  x != 0
-#endif
-E
-"""
-    res = """\
-A
-  always True
-  another line
-B
-C
-  x != 0
-D
-  x != 0
-E
-"""
-    assert preprocess(code, dict(x=1)) == res
-
-
 def test_normalize_path():
     path = "//test//test/test".replace('/', sep)
     assert normalize_path(path) == "/test/test/test".replace('/', sep)
 
     path = "test///test/test".replace('/', sep)
     assert normalize_path(path) == "test/test/test".replace('/', sep)
-
-
-def main():
-    test_make_VIProductVersion()
-    test_fill_template()
-    test_preprocess()
-    test_normalize_path()
-
-
-if __name__ == '__main__':
-    main()