Five GitHub checksRuns in your own CI

Merges that silently break main, caught before they ship.

Mainfast is five GitHub checks for the ways a merge quietly breaks main: a merge commit that drops changes, migrations that fork the history, required checks that protect nothing, CODEOWNERS that drifted, and agent PRs without proof. One config file, MIT licensed.

Install Pricing

GitHub Actions workflow

name: Mainfast Intact
on:
  pull_request:
  push:
    branches-ignore: [main]
permissions:
  contents: read
  checks: write
jobs:
  intact:
    runs-on: ubuntu-latest
    steps:
  # …

Products

Mainfast Intact Free, MIT

Prove that a merge commit did not silently drop changes from main.

Mainfast Migrations Free, MIT

Fail a PR whose migrations would fork the history once merged into main.

Mainfast Rollcall Free, MIT

Find required checks that protect nothing: never ran, skipped, renamed or filtered.

Mainfast Owners Free, MIT

Catch CODEOWNERS drift: unowned files, departed owners, missing teams, dead patterns.

Mainfast Evidence Free, MIT

Proof, not review, for pull requests written by coding agents.

Add one step to a GitHub Actions workflow for each check you want. It runs with your own GITHUB_TOKEN, in your own runners.
Optionally add .mainfast.yml at the repository root, one section per check. Checks read it from the base branch, so a pull request cannot loosen its own check.
Each check posts a check run, a job summary, or one sticky PR comment, and every finding carries a one-line fix.
Require the check (or the commit status for Mainfast Migrations) in branch protection or a ruleset, so a finding blocks the merge.
Found a bug or a false positive, or want something added? Open a GitHub issue: the link is in the footer of every page. Anyone can, free, with no key.

Before you install

Using a coding agent? Point it at /llms.txt: it has the one-line install, the JSON commands and the MCP setup.
A GitHub repository where you can add workflow files under .github/workflows/.
GitHub Actions enabled. The checks run as Actions in your own workflows with your own GITHUB_TOKEN. Mainfast Pro is the hosted GitHub App instead: one install, no workflow files.
Each workflow grants only the permissions its check needs (see the product pages). No administration permission is ever needed.
Mainfast Intact, Mainfast Migrations and the pull_request job of Mainfast Evidence need a checkout with fetch-depth: 0. Mainfast Rollcall and Mainfast Owners need no checkout.
Optional: .mainfast.yml (or .mainfast.yaml) at the repository root. An unknown top-level key is an error, so a typo never silently switches a check back to defaults.
Optional: add the JSON Schema to your editor from https://raw.githubusercontent.com/mainfast/mainfast/main/schema/mainfast.schema.json.
Only Mainfast Owners has an optional extra: an org-token with Organization, Members: read, for org membership and team checks.
Third-party actions in the examples are pinned to full commit SHAs. The CLI of Mainfast Intact needs Node 20+ and git.
The Mainfast actions in the examples use the moving tag @v0, which follows each new release. To stay on one exact version and choose when to update, replace @v0 with a full commit SHA.

Open the installation manual

Pricing

Free

$0the GitHub Actions, for everyone

The five GitHub Actions are free and open source (MIT) for everyone, at any size. They never fail or block a merge for licensing.
On a private repository above 5 active contributors, each Action adds one notice to the job summary. It never fails, blocks or changes a check.
Org-wide shared config with extends is free too. It works today in Mainfast Intact, Mainfast Rollcall and Mainfast Owners.
The hosted GitHub App is also free for public repositories, and for private organisations with up to 5 active contributors.
Active means: opened a pull request or pushed in the last 30 days. Bots are not counted.
No sign-up needed.
Anyone can report bugs, false positives and ideas in GitHub issues, free, with no key. Issues are public, so leave out private code and secrets.

Pricing details

Mainfast Pro

$4per active contributor / month

Active: opened a pull request or pushed in the last 30 days; bots not counted. Install the App, then buy Pro from its dashboard, so the subscription belongs to your organisation.

Mainfast Pro is the hosted GitHub App for private organisations above 5 active contributors, at $4 per active contributor per month.
What you pay for: one install with no workflow files, an org dashboard of findings and trends, Slack and email alerts, cached results, and answers to issues within one business day.
A new install runs in full for 14 days. From day 7 the checks and the dashboard show the date blocking starts.
After that, with no Pro: every hosted check fails, titled "Mainfast Pro needed", and checks nothing. That blocks merges where the check is required. The dashboard shows only the upgrade page until you pay.
Your data stays stored while the App is installed and returns on payment, and open pull requests are re-checked automatically. Uninstalling removes the checks and deletes the data.
If we cannot tell whether you have paid, because of an error or an outage, the checks run normally. A failed payment keeps working until the subscription ends.
The Actions stay free and never block for licensing. A Pro key passed as the MAINFAST_LICENSE secret also removes their notice.

Pricing details