- Stage one real diff and run two tools against it
- Commit from the terminal on your own key, or from an editor button?
- Should your diffs go to a local model or a hosted one?
- If your team writes conventional commits
- Terminal tools and git hooks that run on your own model
- Commit message help inside your editor
- Messages that mislead your reviewers
- Paying for commit message generation
- Matching a commit message generator to how you work
Several of the best-known AI commit message generators are free, MIT-licensed command line tools that run on your own model API key or a local model. If you want control and a tiny bill, start with one of those; if you'd rather not set anything up, use the commit message feature in the editor you already pay for.
That first point shapes everything else on this page. The tool itself is usually free, so the real decisions are where your diff gets sent, who pays for the model, and whether the message comes out in the format your team already agreed on. A generator that writes a lovely sentence in the wrong shape is worse than no generator, because someone has to fix every one by hand.
So don't pick from a feature list. Pick from a test on your own code, which takes well under an hour.
Stage one real diff and run two tools against it
Choose a change you made this week that has a reason behind it, ideally a bug fix. Say you swapped float maths for Python's Decimal in billing/invoice.py because totals on long invoices were drifting by a penny. Stage only that file with git add -p, then check what the tool will see with git diff --staged. That staged diff is all most of these tools read, so it's also all they know.
Now run two different types against the same diff: a command line generator on your own key, and the button in your editor. Don't commit either result. Paste both into a scratch file next to the message you'd have written yourself. A typical pair looks something like this: one says Update invoice.py to use Decimal, the other says fix(billing): use Decimal for invoice totals. Yours probably says fix(billing): stop rounding drift on long invoices, with a body line explaining that customers with many line items saw totals a penny out.
Score each draft against your team's own convention, not your taste:
- Did it choose the right type (fix, feat, refactor, chore, docs) and a scope your repo already uses?
- Is the subject in the imperative mood and inside the length your team keeps to?
- Does it say why the change exists, or only what lines moved?
- Would a reviewer reading
git log --onelinesix months from now understand it without opening the diff?
Repeat with a messy diff that touches three unrelated files. That's where the gap between tools shows. A good generator either writes a sensible summary or makes it obvious the commit should be split; a weak one produces a vague line like "various updates" that tells nobody anything.
Commit from the terminal on your own key, or from an editor button?
This is the biggest fork. Terminal tools and git hooks are usually open source, install in a minute, and call whatever model you configure with your own API key. You control the model, the prompt and often the output template, and they work the same in every editor because they sit on git itself. The cost is a little setup and a key to look after.
Editor and git client features sit inside a product you may already use. There's nothing to configure, the message lands in the commit box where you can edit it, and the AI comes bundled with a plan you pay for. You give up control of the model and, often, of exactly what text gets sent. If you've been weighing editors anyway, our guide to code editors is worth a look before you tie commit messages to one.
A third route exists. Some AI coding assistants commit their own edits as they go, writing the message as a side effect; Aider works this way, committing every change it makes to git. That's handy if the assistant writes most of the code, and noisy if it doesn't.
Should your diffs go to a local model or a hosted one?
A hosted model writes better prose and needs nothing on your machine, but every staged diff leaves your laptop. A local model keeps the code at home and costs nothing per call, at the price of speed, a few gigabytes of disk and messages that can be blander. Look for Ollama in a tool's provider list if local matters to you; OpenCommit lists it, for example.
If you work across version control systems, check that too: aicommit2 handles Jujutsu as well as Git and talks to several providers, including Ollama, ChatGPT, Gemini and Claude.
If your team writes conventional commits
Conventional commits (type(scope): subject) are where these tools earn or lose their keep, because release tooling and changelogs often read those prefixes. A generator that ignores the format creates work for whoever runs the release. Some tools say outright that they write conventional messages; others let you edit the prompt or template until they do. Either is fine. What isn't fine is assuming the format will come out right because the first two examples looked tidy. Run ten commits through it and count the ones you'd have to fix.
Keep your existing commit linter switched on as well. It's the cheapest safety net you've got, and it catches the generator's bad days without anyone having to notice.
Terminal tools and git hooks that run on your own model
aicommits
A small open-source command line tool that reads whatever you've staged and proposes the commit message from it with an AI model.
OpenCommit
Worth a look if you'd like the choice of a local model: an open-source CLI that supports several LLM providers, Ollama among them.
aicommit2
For developers splitting repos between Git and Jujutsu, a reactive command line generator that works with both and several AI providers.
gptcommit
Rather than a separate command, this one lives in git's prepare-commit-msg hook and drafts the message as part of your normal commit.
CodeGPT
Written in Go, this terminal tool writes commit messages and can also hand you a short AI review of the change you're about to commit.
auto-commit
A minimal open-source command line utility with one job: writing your commit messages automatically so you don't have to.
Aider
An AI pair programmer for the terminal that commits each edit it makes to git, writing a sensible message as it goes.
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Commit message help inside your editor
ai-commit (Sitoi)
Teams that follow the Conventional Commits format can try this open-source editor extension, which reviews Git changes through an AI API and writes matching messages.
GitLens
GitKraken's VS Code extension, whose AI features generate commit messages along with pull request descriptions and changelogs.
JetBrains AI Assistant
If your team lives in IntelliJ, PyCharm or another JetBrains IDE, this add-on brings commit message generation in with its other AI features.
Messages that mislead your reviewers
Sending private code to a hosted model without asking. Every staged diff goes to the provider you've configured. For a side project that's fine. For client code, regulated data or anything under a contract with a confidentiality clause, check the policy first, and if the answer's no, use a local model or don't use the tool on that repo. Watch for secrets too: a diff that adds an .env file sends the key along with it.
Messages that describe the diff and miss the why. The model sees changed lines, not the bug report, the Slack thread or the customer who complained. Left alone, it writes "use Decimal for invoice totals" when the history needed "stop rounding drift on long invoices". Treat the draft as a first line and add the reason, the ticket number or the trade-off yourself. That's the part future you will read.
Giant commits. Feed a generator a few thousand lines across a dozen files and you'll get a summary so general it's useless, and on some models the diff gets cut off. Smaller commits fix this, and they were a good habit before AI turned up.
Accepting on autopilot. The first week, everyone reads the draft. By the third week, people hit enter. Wrong types and invented scopes creep into the history and break changelog tooling quietly. A commit linter in CI catches the format; only a human catches a message that's wrong about what changed.
Letting an assistant commit everything. Tools that commit each AI edit leave a trail of tiny commits. Squash them into meaningful ones before you push to a shared branch, or reviewers will drown. The same goes for the tests those assistants write; my list of AI test generation tools covers how to check them.
Do you make AI commit message tools? Tool makers can ask to be considered for a featured place on this list.
Paying for commit message generation
Commit message generation rarely carries a price of its own, so here's the shape of the bill instead. The open-source terminal tools and extensions cost nothing to install. With them, you pay your model provider for usage on your own key, which scales with how many commits you make and how big each diff is. Commit messages are short jobs, so it stays small: one popular CLI's readme estimates its default model costs no more than small change per casual working day. Point the tool at a local model and the per-call cost drops to nothing, though you're paying in hardware and speed.
Editor and git client features work differently. The commit message button comes bundled with an AI plan or add-on, so you're paying a subscription per developer whether you use it for commits or not. GitKraken and JetBrains both mention a free trial on their pages, which gives you time to run the test above before paying.
If you're cost-sensitive across the whole team, the cheapest serious setup is a terminal tool on a local model. If you'd like to see what else is free in AI coding, my roundup of free AI code generators covers that wider ground.
Matching a commit message generator to how you work
Solo developer who wants it working today and doesn't mind a hosted model: a terminal tool on your own API key. It's the lowest bill and the most control, and you'll have it running before your coffee's cold.
Team with private or client code: a CLI or hook that supports a local model, so the diff never leaves the machine. Accept slightly plainer messages as the trade.
Team with a release process built on conventional commits: a tool that writes the format out of the box or lets you edit the template, backed by the commit linter you already run in CI.
Developers who already pay for an AI plan in their IDE or git client: use the built-in button first. If its messages pass the staged-diff test, there's nothing else to buy.
People who let an AI assistant write most of the code: pick an assistant that commits its own edits, then squash before you share. Whichever type you choose, keep writing the why yourself. No model can see it in the diff.
Want your tool on this list? Featured spots and reviews here are paid partnerships. Here's how to partner with me.

