provefab.

Turns labelled GitHub issues into pull requests that arrive green, reviewed by a second model, with their evidence.

Get Pro, €79/moStar on GitHub
inputGitHub issues you label
outputpull requests with their evidence
agentsClaude Code · Codex · Pi
decidesyour fmt, lint and tests
reviewsa second model family
routingcheapest model that fits
runs onyour Mac, your plans or API keys
01How it works

Agents write the code. Your checks decide what ships.

Every issue runs the same line. Each station is deterministic Rust; the agents only ever touch an isolated worktree.

  • You
  • AI agent
  • Provefab
  • Your checks

  1. Label (by you)

    issue #42

    You label an issue. That is the go-ahead.

  2. Route (by Provefab)

    sonnet · gpt-5.5

    Picks the cheapest model that can do the job.

  3. Plan (by an AI agent)

    reproduce first

    An agent reads the code and plans. Bugs are reproduced first.

  4. Implement (by an AI agent)

    +15 −2

    An agent writes the change in an isolated copy, behind a guard.

  5. Check (by your checks)

    failing test, then 42 tests pass

    Your fmt, lint and tests decide. Red goes back to the agent.

    ↺ red test → fix

  6. Review (by an AI agent)

    +1 test

    A model from another family reviews. Each finding becomes a test.

    ↺ finding → test → fix

  7. Pull request (by Provefab)

    PR #43 ✓ ready to merge

    Opened with its evidence. You click merge.

You merge. Pro can auto-merge small, tested changes.

02Why you can trust it

Built so a model can't talk its way past your tests.

A

A guard on every tool call

Agents cannot push, touch CI or secrets, or leave their worktree. Only Provefab commits, with your permissions.

B

Cross-model review

The reviewer runs on a different model family than the implementer, so one model's blind spots don't approve themselves.

C

Tests can't be quietly weakened

A change that deletes or disables tests is flagged in the PR and never merged automatically.

$ provefab status
28 sandbox#10 pr_open waits for your review
29 sandbox#12 merged two models approved
22/22issues turned into PRs while building itself
2model families on every merge
03Pricing

Free to run. Pro when you want it to merge.

Free

Functional Source License, on GitHub
€0
 
  • +Labelled issues become verified pull requests
  • +Your checks, a guard on every agent, cross-model review
  • +Pull requests wait for your review
Star on GitHub
Pro

Pro

Per GitHub organization · unlimited repositories and developers
€79/ month
or €790 / year
In the United States: $89 / month or $890 / year
  • +Everything in Free
  • +A second reviewer on a different model
  • +Merge policies: ready to merge by default, or auto-merge small PRs under seven fail-closed checks
  • +Cost reports: cost per merged PR, per model and repository
Buy monthlyBuy yearly
04Questions
Does my code leave my machine?+

Only to the model providers you already use. Provefab runs on your Mac, with your own Claude, ChatGPT or API logins.

Which plans and workers work?+

Claude Code, Codex and Pi, each through its own unmodified CLI, with your own plan login or your own API key. You choose per model and can switch in one line, or keep both so the API key takes over when the plan hits its limit. For work, use a business plan (Claude Team or Enterprise, ChatGPT Business) or API keys: consumer plans can restrict commercial use.

How does Provefab keep model costs down?+

Jev rates how hard each issue is, how much planning it needs and how risky a mistake would be. Provefab then runs each stage on the cheapest model that meets that level: your plan first, then your API keys by price. Prices update daily. An implementation that keeps failing moves one tier up.

Does it merge without me?+

Not unless you turn it on. By default a pull request arrives green, with its evidence, and waits for your click. Pro can auto-merge small changes under a policy you set: size cap, excluded paths, a test change required.

What happens when the license expires?+

Pull requests keep opening and each one still shows its cost; the second reviewer, auto-merge and cost reports stop.

Does Pro phone home?+

Only to renew your key, and you can turn that off. Auto-merge itself never needs the network.

Can I get a refund?+

Yes. Your first payment is refunded in full if you ask within 14 days. Renewals are not refunded; you can cancel any time and keep Pro until the end of the paid period.

How do I cancel?+

From the Polar customer portal at polar.sh/provefab/portal: sign in with your purchase email, then cancel. You keep Pro until the end of the paid period. The portal also has your invoices and the provefab-pro download.

What is the Functional Source License?+

You can use, change and share Provefab for anything except a competing product. Each version becomes Apache 2.0 two years after its release.