diff --git a/CHANGELOG.md b/CHANGELOG.md
index 7abbf69..d1afa70 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -9,6 +9,12 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## [Unreleased]
+
+### Added
+
+- Initial release of the next-repository-tag-number action.
+
 ## [1.0.1] - 2024-11-04
 
 ### Fixed
diff --git a/next-repository-tag-number/Dockerfile b/next-repository-tag-number/Dockerfile
new file mode 100644
index 0000000..f7fc0fc
--- /dev/null
+++ b/next-repository-tag-number/Dockerfile
@@ -0,0 +1,4 @@
+FROM alpine:latest
+RUN apk add --update --no-cache --no-progress curl jq
+COPY get-next-tag-number.sh /get-next-tag-number.sh
+ENTRYPOINT ["/get-next-tag-number.sh"]
diff --git a/next-repository-tag-number/action.yml b/next-repository-tag-number/action.yml
new file mode 100644
index 0000000..4b045e9
--- /dev/null
+++ b/next-repository-tag-number/action.yml
@@ -0,0 +1,35 @@
+name: Next Repository Tag Number
+description: Get the next tag number for a repository.
+
+inputs:
+  repository_url:
+    description: The URL of the OCI-compatible repository.
+    required: true
+  bearer_token:
+    description: Optional bearer token for repository authentication.
+    required: false
+  initial_number:
+    description: Starting tag number if no tags exist.
+    default: '1'
+    required: false
+  tag_prefix:
+    description: Prefix for the tags.
+    default: 'build-'
+    required: false
+
+outputs:
+  tag:
+    description: The next tag.
+    value: ${{ steps.next-tag.outputs.tag }}
+  number:
+    description: The next tag number.
+    value: ${{ steps.next-tag.outputs.number }}
+
+runs:
+  using: docker
+  image: Dockerfile
+  args:
+    - ${{ inputs.repository_url }}
+    - ${{ inputs.bearer_token }}
+    - ${{ inputs.initial_number }}
+    - ${{ inputs.tag_prefix }}
diff --git a/next-repository-tag-number/get-next-tag-number.sh b/next-repository-tag-number/get-next-tag-number.sh
new file mode 100755
index 0000000..7ad41ea
--- /dev/null
+++ b/next-repository-tag-number/get-next-tag-number.sh
@@ -0,0 +1,34 @@
+#!/usr/bin/env sh
+
+REPOSITORY_URL=$1
+BEARER_TOKEN=$2
+INITIAL_NUMBER=${3:-1}
+TAG_PREFIX=${4:-"build-"}
+
+if [ -n "$BEARER_TOKEN" ]; then
+  AUTH_HEADER="-H \"Authorization: Bearer ${BEARER_TOKEN}\""
+else
+  AUTH_HEADER=""
+fi
+
+TAGS=$(curl -s $AUTH_HEADER "${REPOSITORY_URL}/tags/list" | jq -r '.tags[]' || echo "")
+
+if [ -z "$TAGS" ]; then
+  echo "No existing tags were found. Using initial tag number ${INITIAL_NUMBER}."
+  NEXT_TAG_NUMBER=$INITIAL_NUMBER
+else
+  HIGHEST_TAG=$(echo "$TAGS" | grep -Eo "${TAG_PREFIX}[0-9]+" | sort -V | tail -n 1)
+
+  if [ -z "$HIGHEST_TAG" ]; then
+    echo "No existing tags with the specified prefix were found. Using initial tag number ${INITIAL_NUMBER}."
+    NEXT_TAG_NUMBER=$INITIAL_NUMBER
+  else
+    HIGHEST_TAG_NUMBER=$(echo "$HIGHEST_TAG" | grep -Eo '[0-9]+')
+    NEXT_TAG_NUMBER=$((HIGHEST_TAG_NUMBER + 1))
+  fi
+fi
+
+NEXT_TAG="${TAG_PREFIX}${NEXT_TAG_NUMBER}"
+echo "Next tag: $NEXT_TAG"
+echo "tag=$NEXT_TAG" >> $GITHUB_OUTPUT
+echo "number=$NEXT_TAG_NUMBER" >> $GITHUB_OUTPUT