> ## Documentation Index
> Fetch the complete documentation index at: https://site.aspect.build/llms.txt
> Use this file to discover all available pages before exploring further.

# Bazel Rules

> Aspect's Bazel reference docs covering open-source rulesets for Python, JavaScript, TypeScript, and more, plus linting and shared utilities for hermetic builds.

Bazel is Google's Open Source Build and Test system, which supports many languages.
For two of the most widely used ecosystems, the rulesets the community builds on were written by Aspect, and we maintain them today: `rules_py` for Python, and `rules_js` and `rules_ts` for JavaScript & TypeScript. We also maintain `rules_lint`, which brings linting and formatting to every language under Bazel.

This reference covers those two ecosystems in depth, from first build to advanced patterns, written by the same engineers who wrote the rules.

<Tip>
  New to Bazel?

  * Start with [Bazel 101](/learning/bazel-101) for a language-agnostic introduction.
  * Pick a language section below to get started quickly.
  * Sign up for [commercial support](/services), provided by Aspect as a shared Slack channel.
</Tip>

## Languages & ecosystems

<Columns cols={2}>
  <Card title="Python" icon="python" href="/docs/bazel/python">
    Built and maintained by Aspect: `rules_py`. Hermetic Python interpreters, pinned
    dependencies via `uv`, and Gazelle-generated `BUILD` files. Covers testing,
    virtualenvs, containers, and cross-builds.
  </Card>

  <Card title="JavaScript & TypeScript" icon="js" href="/docs/bazel/javascript">
    Built and maintained by Aspect: `rules_js` and `rules_ts`, with pnpm workspaces.
    Includes integrations for esbuild, webpack, Jest, Cypress, Vite, and Next.js.
  </Card>
</Columns>

<Columns cols={2}>
  <Card title="Linting & Formatting" icon="broom" href="/docs/bazel/linting">
    Built and maintained by Aspect: `rules_lint`. First-class linting and formatting
    for dozens of languages, incremental and cache-aware, with hold-the-line adoption.
  </Card>
</Columns>

## More open source

Beyond these rulesets, Aspect maintains a broad portfolio of open-source Bazel tooling, including the [Aspect CLI](/docs/cli/overview), `aspect-gazelle`, `rules_lint`, and `bazel-lib`. See [Open Source Projects](/docs/bazel/open-source) for the full listing, and [Contributing](/open-source) for how we prioritize community work.