Commit Message Writer

commit-message-writer

Description

Write Conventional Commit messages from a git diff, code snippet, or plain description. Also generates PR titles and 3-bullet PR summaries. Works with any language and any project — no setup, no config.

Use when

"write a commit message"

"what should I commit this as"

"conventional commit for this diff"

"write a PR title and description"

Any git diff or code change needing a message

Supported conventions

Conventional Commits 1.0 (default)

Angular commit format

GitHub squash-merge style

Plain descriptive (no convention)

Request a specific one or it defaults to Conventional Commits.

Input

Paste one of:

A git diff (git diff --staged)

A description of what changed ("I added rate limiting to the API")

Code before/after

Optionally specify:

Convention (defaults to Conventional Commits)

Scope (component, module, or area affected)

Whether this is a breaking change

Output format

## Commit Message
type: [subject]
[body — explains WHY, not just WHAT. Omitted if obvious from subject]
[BREAKING CHANGE: description — only if applicable]
[Closes #123 — only if issue number is known]
PR Title
[short, imperative, under 70 chars]
PR Summary
[What changed]
[Why it changed / what problem it solves]
[Any notable side effects, caveats, or follow-up needed]

Conventional Commits type guide

| Type | When to use | |---|---| | feat | New feature (triggers minor version bump) | | fix | Bug fix (triggers patch version bump) | | docs | Documentation only | | style | Formatting, whitespace — no logic change | | refactor | Restructure without changing behavior | | perf | Performance improvement | | test | Adding or fixing tests | | chore | Build system, CI, dependency updates | | revert | Reverts a prior commit | | ci | CI pipeline changes |

Writing rules

Subject: imperative mood ("add", "fix", "remove" — not "added", "fixed", "removes")

Subject: no period at end

Subject: under 72 characters

Body: explain WHY the change was made, not just what the diff shows

Breaking change: always include BREAKING CHANGE: footer with migration notes

Scope: use the module, file, or feature name (e.g., auth, api, db, ui)

If the diff touches multiple concerns: suggest splitting into multiple commits

Examples

Simple fix

fix(auth): reject expired JWT tokens before checking claims
Previously, token expiry was checked after claim validation,
which allowed attackers to replay expired tokens with valid claims.

New feature with breaking change

feat(api)!: require API key on all public endpoints
BREAKING CHANGE: All requests now require X-API-Key header.
Clients using anonymous access will receive 401. See migration guide.

Dependency update

chore(deps): bump openssl from 1.1.1 to 3.0.8
Addresses CVE-2023-0286 (X.400 address type confusion).
No API changes.

Self-improvement instructions

After each commit message written, note whether the input was a diff, description, or code snippet. After 20 uses, surface the most common missing context that leads to weaker messages.

Simple fix

fix(auth): reject expired JWT tokens before checking claims
Previously, token expiry was checked after claim validation,
which allowed attackers to replay expired tokens with valid claims.

New feature with breaking change

feat(api)!: require API key on all public endpoints
BREAKING CHANGE: All requests now require X-API-Key header.
Clients using anonymous access will receive 401. See migration guide.

Dependency update

chore(deps): bump openssl from 1.1.1 to 3.0.8
Addresses CVE-2023-0286 (X.400 address type confusion).
No API changes.