diff --git a/README.md b/README.md
index c8586b1..5f2a37b 100644
--- a/README.md
+++ b/README.md
@@ -14,21 +14,23 @@ The downside is that equations are not rendered for team members without the Mat
 
 ## How do I install it?
 
-Download and run the script. Restart the Slack client. You're done!
+Get and run the script. Restart the Slack client. You're done!
 
+### Getting the script
 
 ### Mac and Linux
 
 Run the following in a terminal:
 
 ```shell
-curl -OL https://github.com/fsavje/math-with-slack/releases/download/v0.2.5/math-with-slack.sh
-sudo bash math-with-slack.sh
+curl -OL https://raw.githubusercontent.com/psg-mit/math-with-slack/v3/math-with-slack.py
+sudo python math-with-slack.py
 ```
 
-
 ### Windows
 
+!!! Current support for windows is unknown
+
 [Download the script](https://github.com/fsavje/math-with-slack/releases/download/v0.2.5/math-with-slack.bat) and double-click to run. Alternatively, run it in the command prompt with:
 
 ```shell
diff --git a/math-with-slack.py b/math-with-slack.py
old mode 100755
new mode 100644
index 71383a9..a93533d
--- a/math-with-slack.py
+++ b/math-with-slack.py
@@ -15,7 +15,7 @@
 #
 ################################################################################
 
-# Python 2.7
+# Python 2.7 and 3
 
 from __future__ import print_function
 
@@ -28,6 +28,17 @@
 import shutil
 import struct
 import sys
+from distutils.version import LooseVersion
+
+try:
+    # Python 3
+    import urllib.request as urllib_request
+except:
+    # Python 2
+    import urllib as urllib_request
+
+import tarfile
+import tempfile
 
 
 # Math with Slack version
@@ -39,7 +50,9 @@
 
 parser = argparse.ArgumentParser(prog='math-with-slack', description='Inject Slack with MathJax.')
 parser.add_argument('-a', '--app-file', help='Path to Slack\'s \'app.asar\' file.')
-parser.add_argument('-s', '--settings-file', help='Path to Slack\'s \'local-settings.json\' file.')
+parser.add_argument('--mathjax-url', 
+                    help='Url to download mathjax release.', 
+                    default='https://registry.npmjs.org/mathjax/-/mathjax-3.0.1.tgz')
 parser.add_argument('-u', '--uninstall', action='store_true', help='Removes injected MathJax code.')
 parser.add_argument('--version', action='version', version='%(prog)s ' + mws_version)
 args = parser.parse_args()
@@ -58,7 +71,7 @@ def exprint(*args, **kwargs):
     app_path = args.app_file
 elif sys.platform == 'darwin':
     app_path = '/Applications/Slack.app/Contents/Resources/app.asar'
-elif sys.platform == 'linux':
+elif sys.platform.startswith('linux'):
     for test_app_file in [
         '/usr/lib/slack/resources/app.asar',
         '/usr/local/lib/slack/resources/app.asar',
@@ -80,59 +93,10 @@ def exprint(*args, **kwargs):
     exprint('Could not find Slack\'s app.asar file. Please provide path.')
 
 
-# Find path to local-settings.json
-
-if args.settings_file is not None:
-    settings_path = args.settings_file
-elif sys.platform == 'darwin':
-    for test_settings_file in [
-        os.path.expandvars('${HOME}/Library/Application Support/Slack/local-settings.json'),
-        os.path.expandvars('${HOME}/Library/Containers/com.tinyspeck.slackmacgap/Data/Library/Application Support/Slack/local-settings.json')
-    ]:
-        if os.path.isfile(test_settings_file):
-            settings_path = test_settings_file
-            break
-elif sys.platform == 'linux':
-    exprint('Not implemented')
-elif sys.platform == 'win32':
-    settings_path = os.path.expandvars('%AppData%\\Slack\\local-settings.json')
-
-
-# Check so local-settings.json file exists
-
-try:
-    if not os.path.isfile(settings_path):
-        exprint('Cannot find settings file at: ' + settings_path)
-except NameError:
-    exprint('Could not find local-settings.json. Please provide path.')
-
 
 # Print info
 
 print('Using Slack installation at: ' + app_path)
-print('Using local settings file at: ' + settings_path)
-
-
-# Update local settings file
-
-with open(settings_path, mode='r') as settings_file:
-    settings_json = json.load(settings_file)
-
-if args.uninstall:
-    if 'bootSonic.mwsbak' in settings_json:
-        settings_json['bootSonic'] = settings_json['bootSonic.mwsbak']
-        del settings_json['bootSonic.mwsbak']
-else:
-    if 'bootSonic.mwsbak' not in settings_json:
-        settings_json['bootSonic.mwsbak'] = settings_json['bootSonic']
-    settings_json['bootSonic'] = 'never'
-
-try:
-    with open(settings_path, mode='w') as settings_file:
-        json.dump(settings_json, settings_file, separators=(',', ':'))
-except Exception as e:
-    print(e)
-    exprint('Cannot update settings file. Make sure the script has write permissions.')
 
 
 # Remove previously injected code if it exists
@@ -146,12 +110,14 @@ def exprint(*args, **kwargs):
 assert json_binary_size == json_data_size + 4
 json_check = json.loads(json_binary[8:(json_string_size + 8)].decode('utf-8'))
 
+app_backup_path = app_path + '.mwsbak'
+
 if 'MWSINJECT' in json_check['files']:
-    if not os.path.isfile(app_path + '.mwsbak'):
+    if not os.path.isfile(app_backup_path):
         exprint('Found injected code without backup. Please re-install Slack.')
     try:
         os.remove(app_path)
-        shutil.move(app_path + '.mwsbak', app_path)
+        shutil.move(app_backup_path, app_path)
     except Exception as e:
         print(e)
         exprint('Cannot remove previously injected code. Make sure the script has write permissions.')
@@ -159,9 +125,9 @@ def exprint(*args, **kwargs):
 
 # Remove old backup if it exists
 
-if os.path.isfile(app_path + '.mwsbak'):
+if os.path.isfile(app_backup_path):
     try:
-        os.remove(app_path + '.mwsbak')
+        os.remove(app_backup_path)
     except Exception as e:
         print(e)
         exprint('Cannot remove old backup. Make sure the script has write permissions.')
@@ -179,45 +145,76 @@ def exprint(*args, **kwargs):
 # Code to be injected
 
 inject_code = ('\n\n// math-with-slack ' + mws_version + '''
-// https://github.com/fsavje/math-with-slack
+// Inject MathJax 3.
+// Credit to initial implementation: https://github.com/fsavje/math-with-slack
 document.addEventListener('DOMContentLoaded', function() {
-  var mathjax_config = document.createElement('script');
-  mathjax_config.type = 'text/x-mathjax-config';
-  mathjax_config.text = `
-    MathJax.Hub.Config({
-      messageStyle: 'none',
-      extensions: ['tex2jax.js'],
-      jax: ['input/TeX', 'output/HTML-CSS'],
-      tex2jax: {
-        displayMath: [['$$', '$$']],
-        element: 'msgs_div',
-        ignoreClass: 'ql-editor',
-        inlineMath: [['$', '$']],
-        processEscapes: true,
-        skipTags: ['script', 'noscript', 'style', 'textarea', 'pre', 'code']
-      },
-      TeX: {
-        extensions: ['AMSmath.js', 'AMSsymbols.js', 'noErrors.js', 'noUndefined.js']
+
+  function typeset(element) {
+    const MathJax = window.MathJax;
+    MathJax.startup.promise = MathJax.startup.promise
+      .then(() => {console.log(element); return MathJax.typesetPromise(element);})
+      .catch((err) => console.log('Typeset failed: ' + err.message));
+    return MathJax.startup.promise;
+  }
+
+  window.MathJax = {
+    options: {
+        skipHtmlTags: [
+            'script', 'noscript', 'style', 'textarea', 'pre',
+            'code', 'annotation', 'annotation-xml'
+        ],
+    },
+    loader: {
+        paths: {mathjax: 'mathjax/es5'},
+        source: {},
+        require: require,
+        load: [
+            'input/tex-full',
+            'output/svg',
+            '[tex]/noerrors', 
+            '[tex]/noundefined', 
+            '[tex]/boldsymbol'
+        ]
+    },
+    tex: {
+      packages: {'[+]': ['ams', 'color', 'noerrors', 'noundefined', 'boldsymbol']},
+      inlineMath: [['$', '$']],
+      displayMath: [['$$', '$$']],
+    },
+    startup: {
+      ready: () => {
+        MathJax = window.MathJax;
+        MathJax.startup.defaultReady();
+        var entry_observer = new IntersectionObserver(
+          (entries, observer) => {
+            var appearedEntries = entries.filter((entry) => entry.intersectionRatio > 0);
+            if(appearedEntries.length) {
+                console.log(appearedEntries);
+                typeset(appearedEntries.map((entry) => entry.target));
+            }
+          }, 
+          { root: document.body }
+        );
+        var target = document.body.addEventListener("DOMNodeInserted", 
+            function(event) {
+                var target = event.relatedNode;
+                if(target && typeof target.getElementsByClassName === 'function') {
+                    // span.c-message_kit__text for messages in the Threads View
+                    // span.c-message__body for messages in the chats (i.e. direct messages)
+                    var messages = target.querySelectorAll('span.c-message__body, span.c-message_kit__text, div.p-rich_text_block');
+                    for (var i = 0; i < messages.length; i++) {
+                        msg = messages[i];
+                        entry_observer.observe(msg);
+                    }
+                }
+            }
+        );
       }
-    });
-  `;
-
-  var mathjax_observer = document.createElement('script');
-  mathjax_observer.type = 'text/x-mathjax-config';
-  mathjax_observer.text = `
-    var target = document.querySelector('#messages_container');
-    var options = { attributes: false, childList: true, characterData: true, subtree: true };
-    var observer = new MutationObserver(function (r, o) { MathJax.Hub.Queue(['Typeset', MathJax.Hub]); });
-    observer.observe(target, options);
-  `;
-
-  var mathjax_script = document.createElement('script');
-  mathjax_script.type = 'text/javascript';
-  mathjax_script.src = 'https://cdnjs.cloudflare.com/ajax/libs/mathjax/2.7.5/MathJax.js';
-
-  document.head.appendChild(mathjax_config);
-  document.head.appendChild(mathjax_observer);
-  document.head.appendChild(mathjax_script);
+    },
+  };
+
+  // Import mathjax
+  $MATH_JAX_STUB$
 });
 ''').encode('utf-8')
 
@@ -225,7 +222,7 @@ def exprint(*args, **kwargs):
 # Make backup
 
 try:
-    shutil.move(app_path, app_path + '.mwsbak')
+    shutil.copy(app_path, app_backup_path)
 except Exception as e:
     print(e)
     exprint('Cannot make backup. Make sure the script has write permissions.')
@@ -233,7 +230,7 @@ def exprint(*args, **kwargs):
 
 # Get file info
 
-with open(app_path + '.mwsbak', mode='rb') as ori_app_fp:
+with open(app_backup_path, mode='rb') as ori_app_fp:
     (header_data_size, json_binary_size) = struct.unpack('<II', ori_app_fp.read(8))
     assert header_data_size == 4
     json_binary = ori_app_fp.read(json_binary_size)
@@ -245,23 +242,118 @@ def exprint(*args, **kwargs):
 assert json_binary_size == json_data_size + 4
 json_header = json.loads(json_binary[8:(json_string_size + 8)].decode('utf-8'))
 assert 'MWSINJECT' not in json_header['files']
-ori_ssbinterop_size = json_header['files']['dist']['files']['ssb-interop.bundle.js']['size']
-ori_ssbinterop_offset = int(json_header['files']['dist']['files']['ssb-interop.bundle.js']['offset'])
 
+def read_file_from_asar(file_offset, file_size):
+    with open(app_backup_path, mode='rb') as ori_app_fp:
+        ori_app_fp.seek(file_offset + ori_data_offset)
+        binary = ori_app_fp.read(file_size)
+        return binary
+
+def read_package_json():
+    package_json_desp = json_header['files']['package.json']
+    binary = read_file_from_asar(int(package_json_desp['offset']), int(package_json_desp['size']))
+    return json.loads(binary)
+
+def read_slack_version():
+    package_json = read_package_json()
+    return LooseVersion(package_json['version'])
+
+slack_version = read_slack_version()
+
+if LooseVersion('4.3') <= slack_version < LooseVersion('4.4'):
+    injected_file_name = 'main-preload-entry-point.bundle.js'
+    include_mathjax_inline = False
+elif LooseVersion('4.4') <= slack_version < LooseVersion('4.6'):
+    injected_file_name = 'preload.bundle.js'
+    include_mathjax_inline = False
+elif LooseVersion('4.6') <= slack_version:
+    injected_file_name = 'preload.bundle.js'
+    include_mathjax_inline = True
+else:
+    exprint("Unsupported Slack Version {}.".format(slack_version))
+
+def split_path_to_components(path):
+    dirs = []
+    while True:
+        path, dir = os.path.split(path)
+        if dir != "":
+            dirs.append(dir)
+        else:
+            if path != "":
+                dirs.append(dir)
+            break
+    dirs.reverse()
+    if dirs == ['.']:
+        return dirs
+    else:
+        return ['.'] + dirs
+
+def dir_to_json_header(root_dir, initial_offset):
+    """Returns the json header for `root_dir`.
+    
+    Args:
+        - root_dir: the root_dir 
+        - initial_offset: a number that is added to all offset of files
+
+    Returns:
+        a tuple of (result, file_paths), where result is a dict containing
+        the json header, and file_paths is a list of file paths in order 
+        that should be appended to the end of the .asar file. 
+    """
+    file_paths = []
+    result = {"files": {}}
+    offset = initial_offset
+    for parent_abs, dirs, files in os.walk(root_dir):
+        parent = os.path.relpath(parent_abs, root_dir)
+        parent_components = split_path_to_components(parent)
+        rdict = result
+        for dir_component in parent_components[:-1]:
+            rdict = rdict["files"][dir_component]
+        rdict["files"][parent_components[-1]] = {"files": {}}
+        for file in files:
+            file_path = os.path.join(parent_abs, file)
+            file_paths.append(file_path)
+            size = os.path.getsize(file_path)
+            rdict["files"][parent_components[-1]]["files"][file] = {'size': size, 'offset': str(offset)}
+            offset += size
+    return result, file_paths
+
+
+ori_injected_file_size = json_header['files']['dist']['files'][injected_file_name]['size']
+ori_injected_file_offset = int(json_header['files']['dist']['files'][injected_file_name]['offset'])
+
+# Download MathJax, currently assumes downloaded file is a tar called package.tar
+
+mathjax_tar_name, headers = urllib_request.urlretrieve(args.mathjax_url)
+mathjax_tmp_dir = tempfile.mkdtemp()
+mathjax_tar = tarfile.open(mathjax_tar_name)
+mathjax_tar.extractall(path=mathjax_tmp_dir)
+mathjax_tar.close()
+mathjax_dir = os.path.join(mathjax_tmp_dir, "package")
+if include_mathjax_inline:
+    mathjax_src_path = os.path.join(mathjax_dir, "es5/tex-svg-full.js")
+    with open(mathjax_src_path, "r+") as mathjax_src_file:
+        mathjax_src = mathjax_src_file.read().encode('utf-8')
+    append_file_paths = []
+else:
+    mathjax_json_header, append_file_paths = dir_to_json_header(mathjax_dir, ori_data_size + ori_injected_file_size + len(inject_code))
+    json_header["files"]["node_modules"]["files"]["mathjax"] = mathjax_json_header["files"]["."]
+    mathjax_src = "require('mathjax/es5/startup.js');"
+
+inject_code = inject_code.replace(b"$MATH_JAX_STUB$", mathjax_src)
 
 # Modify JSON data
 
 json_header['files']['MWSINJECT'] = json_header['files']['LICENSE']
-json_header['files']['dist']['files']['ssb-interop.bundle.js']['size'] = ori_ssbinterop_size + len(inject_code)
-json_header['files']['dist']['files']['ssb-interop.bundle.js']['offset'] = str(ori_data_size)
-
+json_header['files']['dist']['files'][injected_file_name]['size'] = ori_injected_file_size + len(inject_code)
+json_header['files']['dist']['files'][injected_file_name]['offset'] = str(ori_data_size)
 
 # Write new app.asar file
 
 new_json_header = json.dumps(json_header, separators=(',', ':')).encode('utf-8')
 new_json_header_padding = (4 - len(new_json_header) % 4) % 4
 
-with open(app_path + '.mwsbak', mode='rb') as ori_app_fp, \
+with open(app_backup_path, mode='rb') as ori_app_fp, \
      open(app_path, mode='wb') as new_app_fp:
     # Header
     new_app_fp.write(struct.pack('<I', 4))
@@ -273,16 +365,21 @@ def exprint(*args, **kwargs):
     # Old data
     ori_app_fp.seek(ori_data_offset)
     shutil.copyfileobj(ori_app_fp, new_app_fp)
-    # Modified ssb-interop.bundle.js
-    ori_app_fp.seek(ori_data_offset + ori_ssbinterop_offset)
-    copy_until = ori_app_fp.tell() + ori_ssbinterop_size
+    # Modified injected_file
+    ori_app_fp.seek(ori_data_offset + ori_injected_file_offset)
+    copy_until = ori_app_fp.tell() + ori_injected_file_size
     while ori_app_fp.tell() < copy_until:
         new_app_fp.write(ori_app_fp.read(min(65536, copy_until - ori_app_fp.tell())))
     new_app_fp.write(inject_code)
-
+    # Append MathJax files in sequence
+    new_app_fp.seek(0, 2)
+    for append_file_path in append_file_paths:
+        with open(append_file_path, 'rb') as append_file:
+            new_app_fp.write(append_file.read())
 
 # We are done
 
+shutil.rmtree(mathjax_tmp_dir)
 print('Install successful. Please restart Slack.')
 sys.exit(0)