Mergify

Mergify is a GitHub-native merge automation platform built around its merge queue. Comment @mergifyio queue on a PR and it updates the branch against main, runs your CI on the exact code that will merge, and lands it when checks pass. A .mergify.yml unlocks parallel queues, batching (with automatic bisection to isolate the red PR on failure), priority lanes so hotfixes skip the line, and scheduled merge freezes for releases. Bundled CI Insights and a Test Engine add flaky-test detection with auto-retry and quarantine. It is free for open source and for teams up to 5 users; paid plans are $21 per seat per month.

The honest picture: Mergify only exists on GitHub, and GitHub's own native merge queue is free and improving — the pitch is Mergify's richer queue semantics, not the queue concept itself. Misconfigured queue rules can stall merges silently, and community reports show activation gaps where the app posts ready checks but never enqueues. For a single low-traffic repo, the native queue plus branch protection is usually enough; Mergify earns its keep at monorepo scale.

Install the Mergify GitHub App on your repositories, then commit a .mergify.yml with your queue rules. Single repos work with just a @mergifyio queue comment.