> ## 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.

# Linting & Formatting

[rules\_lint](https://github.com/aspect-build/rules_lint), built and maintained by Aspect, integrates linting and formatting as first-class concepts under Bazel.

## Why rules\_lint

* **No changes needed to rulesets.** Works with the Bazel rules you already use.
* **No changes needed to BUILD files.** No lint wrapper macros, and lint doesn't appear in `bazel query` output. Users simply lint their existing `*_library` targets.
* **Incremental.** Lint checks (including producing fixes) run as normal Bazel actions, so they support Remote Execution and their outputs land in the Remote Cache.
* **Lint changes only.** It's fine if your repository has a lot of existing issues; you don't need to fix or suppress them all to start linting new changes. We call this the "Water Leak Principle": always fix the leak before mopping the spill.
* **Formats files Bazel doesn't know about.** Formatting runs directly on the file tree, so there's no need to create targets for your shell scripts just to format them.
* **Honors your existing configuration files.** The same config the tools use outside Bazel (for example, in your editor) applies under Bazel.

## Supported tools

Formatters and linters ship for dozens of languages, including:

| Language                        | Formatter            | Linter(s)                        |
| ------------------------------- | -------------------- | -------------------------------- |
| JavaScript / TypeScript         | Prettier             | ESLint                           |
| Python                          | ruff                 | ruff, flake8, pylint, bandit, ty |
| C / C++                         | clang-format         | clang-tidy, cppcheck             |
| Go                              | gofmt / gofumpt      |                                  |
| Java                            | google-java-format   | PMD, Checkstyle, Spotbugs        |
| Kotlin                          | ktfmt                | ktlint                           |
| Rust                            | rustfmt              | clippy                           |
| Shell                           | shfmt                | shellcheck                       |
| Starlark                        | Buildifier           | Buildifier                       |
| Protocol Buffers                | buf                  | buf lint                         |
| Markdown, YAML, JSON, HTML, CSS | Prettier and friends | Vale, yamllint, Stylelint        |

See the [full table in the repository](https://github.com/aspect-build/rules_lint#supported-tools); new tools are added frequently.

## Running under the Aspect CLI

The [`aspect lint`](/docs/cli/tasks/lint) and [`aspect format`](/docs/cli/tasks/format) tasks are the easiest way to run rules\_lint: hold-the-line linting that only fails on violations you introduced, and formatting for just the files changed in your PR. Results can be surfaced by [Marvin](/platform/marvin) as status checks, review comments, and suggested fixes on GitHub and GitLab, or as failing tests.

## API reference

Per-linter configuration references live alongside each language:

* JavaScript: [ESLint](/docs/bazel/javascript/aspect_rules_lint/lint_eslint), [Stylelint](/docs/bazel/javascript/aspect_rules_lint/lint_stylelint)
* Python: [ruff](/docs/bazel/python/aspect_rules_lint/lint_ruff), [flake8](/docs/bazel/python/aspect_rules_lint/lint_flake8), [pylint](/docs/bazel/python/aspect_rules_lint/lint_pylint), [ty](/docs/bazel/python/aspect_rules_lint/lint_ty)