Hello, I’m Marvin, your friendly build system robot. I help developers fill Bazel usability gaps with the Aspect Extension Language (AXL).

Bazel is fast, scalable, and battle-tested in the enterprise.
But anyone who’s used it knows: some important workflows are… missing, awkward, or just not adapted to your organization.
Coverage. Formatting. Linting. Test reporting. Documentation. Release automation.

That’s where AXL extensions come in.
They extend the build system in small, composable tasks that solve the real problems Bazel users run into every day.

AXL (Aspect Extension Language) is a dialect of Starlark — the same language Bazel itself uses.
That means extensions are:

• 🔎 Familiar: if you’ve ever read a Bazel BUILD file or rule, AXL will be readable.
• 🔒 Safe and deterministic: no hidden side effects, no unbounded execution — perfect for reproducible builds.
• 🧩 Composable: tasks can interact with Bazel’s query & build APIs while staying lightweight and easy to share.

By using Starlark under the hood, AXL makes it possible to write high-level workflow automation that still feels native to Bazel. This is the Bazel equivalent of Buck2's https://buck2.build/docs/bxl/.

Some things that are possible using AXL:

• 🔍 Impacted Targets → drive bazel-diff to know exactly which targets are affected by your changes.
• 📊 Coverage → a saner replacement for bazel coverage, with incremental coverage and CI-friendly LCOV output.
• 🧹 Format → run multi-language formatters only on files you actually changed.
• 🧪 Test → wrap bazel test, generate compact execlogs, publish artifacts for CI, and comment directly on your pull requests when tests fail.
• 🏗️ Build → customize Bazel’s progress messages, support multiple BES backends, and stream execlogs in real time.
• 🚚 Delivery → release or publish build outputs, optionally only if they’ve changed.
• 🛠️ Gazelle → run Gazelle as a proper extension task,
• 🧭 Lint → run linters as Bazel aspects, cacheable and review-friendly.
• 📚 Docgen → build and package documentation targets across a repo without a target that "depends on the world".

• 🧩 Aspect-reviewed contrib plugins — lightweight, discoverable, and each with its own maturity guidance.
• 🧪 Room to experiment — not every extension is “enterprise stable.". Each plugin shows its maturity (e.g. v0.x or EXPERIMENTAL in the description).
• 🌱 Community participation — most plugins start inside a company; the best ones get shared here.

We care about fast time-to-value.
Every extension is:

• Easy to clone or install
• Ready to run in minutes
• Documented with a clear README.md

If you try one and it doesn’t help you immediately, Marvin wants to hear about it.

• 💡 Have an internal script or extension? Contribute it here!
• 🤝 Share feedback — Marvin loves PRs, issues, and community discussions.