---
obj: application
repo: https://github.com/astral-sh/ruff
website: https://docs.astral.sh/ruff
rev: 2025-05-19
---

# ruff
An extremely fast Python linter and code formatter, written in Rust.

## The Ruff Linter
The Ruff Linter is an extremely fast Python linter designed as a drop-in replacement for [Flake8](https://pypi.org/project/flake8/) (plus dozens of plugins), [isort](https://pypi.org/project/isort/), [pydocstyle](https://pypi.org/project/pydocstyle/), [pyupgrade](https://pypi.org/project/pyupgrade/), [autoflake](https://pypi.org/project/autoflake/), and more.

### `ruff check`
`ruff check` is the primary entrypoint to the Ruff linter. It accepts a list of files or directories, and lints all discovered Python files, optionally fixing any fixable errors. When linting a directory, Ruff searches for Python files recursively in that directory and all its subdirectories:

```console
$ ruff check                  # Lint files in the current directory.
$ ruff check --fix            # Lint files in the current directory and fix any fixable errors.
$ ruff check --watch          # Lint files in the current directory and re-lint on change.
$ ruff check path/to/code/    # Lint files in `path/to/code`.
```

## The Ruff Formatter
The Ruff formatter is an extremely fast Python code formatter designed as a drop-in replacement for [Black](https://pypi.org/project/black/), available as part of the `ruff` CLI via `ruff format`.

### `ruff format`
`ruff format` is the primary entrypoint to the formatter. It accepts a list of files or directories, and formats all discovered Python files:

```shell
ruff format                   # Format all files in the current directory.
ruff format path/to/code/     # Format all files in `path/to/code` (and any subdirectories).
ruff format path/to/file.py   # Format a single file.
```

Similar to Black, running `ruff format /path/to/file.py` will format the given file or directory in-place, while `ruff format --check /path/to/file.py` will avoid writing any formatted files back, and instead exit with a non-zero status code upon detecting any unformatted files.

For the full list of supported options, run `ruff format --help`.

## Configuration
ruff can be configured via `ruff.toml` config file. See [here](https://docs.astral.sh/ruff/settings/) for a reference of all config parameters.