API Changelog Generator — Automatically Detect Breaking Changes and Write Release Notes
Convert API change descriptions into structured Keep-a-Changelog format. Enter a version, date, and one change per line prefixed with its type (added, changed, deprecated, removed, fixed, or security). The tool instantly groups them into the canonical section order and outputs a ready-to-paste CHANGELOG.md block. Supports four real-world presets for REST API releases, breaking changes, patch releases, and unreleased work. Free and runs entirely in your browser.
How to Use API Changelog Generator — Automatically Detect Breaking Changes and Write Release Notes
How to Use the API Changelog Entry Generator:
Load a Preset (Optional): Click any preset at the top to pre-fill all fields with a realistic example. REST API release shows a minor version with new endpoints. Breaking change demonstrates a major version with removed routes. Patch release covers bug fixes and security patches. Unreleased shows how to maintain an [Unreleased] section at the top of your CHANGELOG.md. Each preset is fully editable after loading.
Enter a Version Number: Type a semantic version number such as 2.4.0 in the Version field. For work that has not yet shipped, type Unreleased — this follows the Keep-a-Changelog convention of maintaining an [Unreleased] section that accumulates changes until the next release.
Set the Release Date: The Date field is pre-filled with today's date in ISO 8601 format (YYYY-MM-DD) as required by the Keep-a-Changelog specification. Update it to the planned or actual release date. Leave the field clear to omit the date from the heading.
Add a Compare URL (Optional): Paste a GitHub, GitLab, or Bitbucket comparison URL between the previous version and the current version. For example: https://github.com/org/repo/compare/v2.3.0...v2.4.0. When provided, the version heading becomes a link in the output — a Keep-a-Changelog best practice that lets readers browse the exact diff for every release.
Enter Change Entries: In the Change Entries textarea, add one entry per line. Each line should start with a type prefix followed by a colon and the change description. The supported prefixes are: added (or feat, new), changed (or update, modify), deprecated, removed (or delete, breaking), fixed (or fix, bug, bugfix, hotfix, patch), and security (or sec, cve, vuln). You can also use bracket notation such as [added] or [fixed]. Lines without a recognised prefix are grouped under Changed by default.
Read the Output: The right panel shows the formatted CHANGELOG.md block in real time. Changes are automatically grouped into the canonical section order defined by Keep-a-Changelog: Added, Changed, Deprecated, Removed, Fixed, Security. Each section only appears if it has at least one entry.
Check Warnings: If a line uses an unrecognised type prefix, a warning appears above the output identifying the line number and fallback type used. This lets you spot and correct typos without losing any entries.
Copy or Download: Click Copy to copy the formatted block to the clipboard and paste it directly into your CHANGELOG.md. Click .md to download a standalone CHANGELOG.md file containing only the generated block, useful for code review attachments or release documentation.
Common Use Cases:
- API release documentation: Format all changes for an API release into the standard Keep-a-Changelog structure before pushing to your repository.
- PR description generation: Generate a structured change summary for the pull request body or GitHub Release notes.
- Onboarding developers: Use presets to teach new team members the correct format for changelog entries before they start contributing.
- Backfilling changelogs: Quickly format historical release notes collected from commit messages or Jira tickets into consistent changelog entries.
- Breaking change communication: Use the Breaking change preset as a template when planning a major version with endpoint removals.
Tips and Best Practices:
- Follow semantic versioning (semver.org): increment the patch version for fixes, minor for backwards-compatible additions, and major for breaking changes.
- Use Unreleased as the version string while a release is in progress — replace it with the version number and date on the day you ship.
- Keep each entry to a single, concise sentence. Describe the change from the API consumer's perspective, not the implementation detail.
- Use the deprecated section to give consumers advance notice before removing an endpoint. Always pair a deprecated entry with a migration path in the description.
- Avoid words like "various", "several", or "misc" in entries — each change should be specific enough that a consumer can act on it.
Frequently Asked Questions
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