An extremely fast Python linter, written in Rust.

Programming language: Rust
License: MIT License

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An extremely fast Python linter, written in Rust.

Linting the CPython codebase from scratch.

  • ⚑️ 10-100x faster than existing linters
  • 🐍 Installable via pip
  • 🀝 Python 3.10 compatibility
  • πŸ› οΈ pyproject.toml support
  • πŸ“¦ Built-in caching, to avoid re-analyzing unchanged files
  • πŸ”§ --fix support, for automatic error correction (e.g., automatically remove unused imports)
  • πŸ‘€ --watch support, for continuous file monitoring
  • βš–οΈ Near-parity with the built-in Flake8 rule set
  • πŸ”Œ Native re-implementations of popular Flake8 plugins, like flake8-docstrings (pydocstyle)

Ruff aims to be orders of magnitude faster than alternative tools while integrating more functionality behind a single, common interface. Ruff can be used to replace Flake8 (plus a variety of plugins), pydocstyle, yesqa, and even a subset of pyupgrade and autoflake all while executing tens or hundreds of times faster than any individual tool.

(Coming from Flake8? Try flake8-to-ruff to automatically convert your existing configuration.)

Ruff is actively developed and used in major open-source projects like Zulip, pydantic, and Saleor.

Read the launch blog post.

Table of Contents

  1. Installation and Usage
  2. Configuration
  3. Supported Rules
    1. Pyflakes
    2. pycodestyle
    3. pydocstyle
    4. pyupgrade
    5. pep8-naming
    6. flake8-comprehensions
    7. flake8-bugbear
    8. flake8-builtins
    9. flake8-print
    10. flake8-quotes
    11. flake8-annotations
    12. Ruff-specific rules
    13. Meta rules
  4. Editor Integrations
  5. FAQ
  6. Development
  7. Releases
  8. Benchmarks
  9. License
  10. Contributing

Installation and Usage


Available as ruff on PyPI:

pip install ruff


To run Ruff, try any of the following:

ruff path/to/code/to/check.py
ruff path/to/code/
ruff path/to/code/*.py

You can run Ruff in --watch mode to automatically re-run on-change:

ruff path/to/code/ --watch

Ruff also works with pre-commit:

  - repo: https://github.com/charliermarsh/ruff-pre-commit
    rev: v0.0.108
      - id: ruff

<!-- TODO(charlie): Remove this message a few versions after v0.0.86. --> Note: prior to v0.0.86, ruff-pre-commit used lint (rather than ruff) as the hook ID.


Ruff is configurable both via pyproject.toml and the command line. If left unspecified, the default configuration is equivalent to:

line-length = 88

# Enable Flake's "E" and "F" codes by default.
select = ["E", "F"]
ignore = []

# Exclude a variety of commonly ignored directories.
exclude = [
per-file-ignores = {}

# Allow unused variables when underscore-prefixed.
dummy-variable-rgx = "^(_+|(_+[a-zA-Z0-9_]*[a-zA-Z0-9]+?))$"

# Assume Python 3.10.
target-version = "py310"

As an example, the following would configure Ruff to (1) avoid checking for line-length violations (E501) and (2) ignore unused import rules in __init__.py files:

select = ["E", "F"]

# Never enforce `E501`.
ignore = ["E501"]

# Ignore `F401` violations in any `__init__.py` file, and in `path/to/file.py`.
per-file-ignores = {"__init__.py" = ["F401"], "path/to/file.py" = ["F401"]}

Plugin configurations should be expressed as subsections, e.g.:

# Add "Q" to the list of enabled codes.
select = ["E", "F", "Q"]

docstring-quotes = "double"

Alternatively, common configuration settings can be provided via the command-line:

ruff path/to/code/ --select F401 --select F403

See ruff --help for more:

ruff: An extremely fast Python linter.

Usage: ruff [OPTIONS] <FILES>...


      --config <CONFIG>
          Path to the `pyproject.toml` file to use for configuration
  -v, --verbose
          Enable verbose logging
  -q, --quiet
          Only log errors
  -s, --silent
          Disable all logging (but still exit with status code "1" upon detecting errors)
  -e, --exit-zero
          Exit with status code "0", even upon detecting errors
  -w, --watch
          Run in watch mode by re-running whenever files change
          Attempt to automatically fix lint errors
  -n, --no-cache
          Disable cache reads
      --select <SELECT>
          List of error codes to enable
      --extend-select <EXTEND_SELECT>
          Like --select, but adds additional error codes on top of the selected ones
      --ignore <IGNORE>
          List of error codes to ignore
      --extend-ignore <EXTEND_IGNORE>
          Like --ignore, but adds additional error codes on top of the ignored ones
      --exclude <EXCLUDE>
          List of paths, used to exclude files and/or directories from checks
      --extend-exclude <EXTEND_EXCLUDE>
          Like --exclude, but adds additional files and directories on top of the excluded ones
      --per-file-ignores <PER_FILE_IGNORES>
          List of mappings from file pattern to code to exclude
      --format <FORMAT>
          Output serialization format for error messages [default: text] [possible values: text, json]
          See the files ruff will be run against with the current settings
          See ruff's settings
          Enable automatic additions of noqa directives to failing lines
      --dummy-variable-rgx <DUMMY_VARIABLE_RGX>
          Regular expression matching the name of dummy variables
      --target-version <TARGET_VERSION>
          The minimum Python version that should be supported
      --stdin-filename <STDIN_FILENAME>
          The name of the file when passing it through stdin
  -h, --help
          Print help information
  -V, --version
          Print version information

Excluding files

Exclusions are based on globs, and can be either:

  • Single-path patterns, like .mypy_cache (to exclude any directory named .mypy_cache in the tree), foo.py (to exclude any file named foo.py), or foo_*.py (to exclude any file matching foo_*.py ).
  • Relative patterns, like directory/foo.py (to exclude that specific file) or directory/*.py (to exclude any Python files in directory). Note that these paths are relative to the project root (e.g., the directory containing your pyproject.toml).

Ignoring errors

To omit a lint check entirely, add it to the "ignore" list via --ignore or --extend-ignore, either on the command-line or in your project.toml file.

To ignore an error in-line, Ruff uses a noqa system similar to Flake8. To ignore an individual error, add # noqa: {code} to the end of the line, like so:

# Ignore F841.
x = 1  # noqa: F841

# Ignore E741 and F841.
i = 1  # noqa: E741, F841

# Ignore _all_ errors.
x = 1  # noqa

Note that, for multi-line strings, the noqa directive should come at the end of the string, and will apply to the entire body, like so:

"""Lorem ipsum dolor sit amet.

Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.
"""  # noqa: E501

Ruff supports several workflows to aid in noqa management.

First, Ruff provides a special error code, M001, to enforce that your noqa directives are "valid", in that the errors they say they ignore are actually being triggered on that line (and thus suppressed). You can run ruff /path/to/file.py --extend-select M001 to flag unused noqa directives.

Second, Ruff can automatically remove unused noqa directives via its autofix functionality. You can run ruff /path/to/file.py --extend-select M001 --fix to automatically remove unused noqa directives.

Third, Ruff can automatically add noqa directives to all failing lines. This is useful when migrating a new codebase to Ruff. You can run ruff /path/to/file.py --add-noqa to automatically add noqa directives to all failing lines, with the appropriate error codes.

Supported Rules

Regardless of the rule's origin, Ruff re-implements every rule in Rust as a first-party feature.

By default, Ruff enables all E and F error codes, which correspond to those built-in to Flake8.

The πŸ›  emoji indicates that a rule is automatically fixable by the --fix command-line option.

<!-- Sections automatically generated by cargo dev generate-rules-table. --> <!-- Begin auto-generated sections. -->


For more, see Pyflakes on PyPI.

Code Name Message Fix
F401 UnusedImport ... imported but unused πŸ› 
F402 ImportShadowedByLoopVar Import ... from line 1 shadowed by loop variable
F403 ImportStarUsed from ... import * used; unable to detect undefined names
F404 LateFutureImport from __future__ imports must occur at the beginning of the file
F405 ImportStarUsage ... may be undefined, or defined from star imports: ...
F406 ImportStarNotPermitted from ... import * only allowed at module level
F407 FutureFeatureNotDefined Future feature ... is not defined
F541 FStringMissingPlaceholders f-string without any placeholders
F601 MultiValueRepeatedKeyLiteral Dictionary key literal repeated
F602 MultiValueRepeatedKeyVariable Dictionary key ... repeated
F621 ExpressionsInStarAssignment Too many expressions in star-unpacking assignment
F622 TwoStarredExpressions Two starred expressions in assignment
F631 AssertTuple Assert test is a non-empty tuple, which is always True
F632 IsLiteral Use == and != to compare constant literals πŸ› 
F633 InvalidPrintSyntax Use of >> is invalid with print function
F634 IfTuple If test is a tuple, which is always True
F701 BreakOutsideLoop break outside loop
F702 ContinueOutsideLoop continue not properly in loop
F704 YieldOutsideFunction yield or yield from statement outside of a function
F706 ReturnOutsideFunction return statement outside of a function/method
F707 DefaultExceptNotLast An except: block as not the last exception handler
F722 ForwardAnnotationSyntaxError Syntax error in forward annotation: ...
F821 UndefinedName Undefined name ...
F822 UndefinedExport Undefined name ... in __all__
F823 UndefinedLocal Local variable ... referenced before assignment
F831 DuplicateArgumentName Duplicate argument name in function definition
F841 UnusedVariable Local variable ... is assigned to but never used
F901 RaiseNotImplemented raise NotImplemented should be raise NotImplementedError πŸ› 


For more, see pycodestyle on PyPI.

Code Name Message Fix
E402 ModuleImportNotAtTopOfFile Module level import not at top of file
E501 LineTooLong Line too long (89 > 88 characters)
E711 NoneComparison Comparison to None should be cond is None
E712 TrueFalseComparison Comparison to True should be cond is True
E713 NotInTest Test for membership should be not in
E714 NotIsTest Test for object identity should be is not
E721 TypeComparison Do not compare types, use isinstance()
E722 DoNotUseBareExcept Do not use bare except
E731 DoNotAssignLambda Do not assign a lambda expression, use a def
E741 AmbiguousVariableName Ambiguous variable name: ...
E742 AmbiguousClassName Ambiguous class name: ...
E743 AmbiguousFunctionName Ambiguous function name: ...
E902 IOError IOError: ...
E999 SyntaxError SyntaxError: ...
W292 NoNewLineAtEndOfFile No newline at end of file
W605 InvalidEscapeSequence Invalid escape sequence: '\c'


For more, see pydocstyle on PyPI.

Code Name Message Fix
D100 PublicModule Missing docstring in public module
D101 PublicClass Missing docstring in public class
D102 PublicMethod Missing docstring in public method
D103 PublicFunction Missing docstring in public function
D104 PublicPackage Missing docstring in public package
D105 MagicMethod Missing docstring in magic method
D106 PublicNestedClass Missing docstring in public nested class
D107 PublicInit Missing docstring in __init__
D200 FitsOnOneLine One-line docstring should fit on one line
D201 NoBlankLineBeforeFunction No blank lines allowed before function docstring (found 1) πŸ› 
D202 NoBlankLineAfterFunction No blank lines allowed after function docstring (found 1) πŸ› 
D203 OneBlankLineBeforeClass 1 blank line required before class docstring πŸ› 
D204 OneBlankLineAfterClass 1 blank line required after class docstring πŸ› 
D205 BlankLineAfterSummary 1 blank line required between summary line and description πŸ› 
D206 IndentWithSpaces Docstring should be indented with spaces, not tabs
D207 NoUnderIndentation Docstring is under-indented πŸ› 
D208 NoOverIndentation Docstring is over-indented πŸ› 
D209 NewLineAfterLastParagraph Multi-line docstring closing quotes should be on a separate line πŸ› 
D210 NoSurroundingWhitespace No whitespaces allowed surrounding docstring text πŸ› 
D211 NoBlankLineBeforeClass No blank lines allowed before class docstring πŸ› 
D212 MultiLineSummaryFirstLine Multi-line docstring summary should start at the first line
D213 MultiLineSummarySecondLine Multi-line docstring summary should start at the second line
D214 SectionNotOverIndented Section is over-indented ("Returns") πŸ› 
D215 SectionUnderlineNotOverIndented Section underline is over-indented ("Returns") πŸ› 
D300 UsesTripleQuotes Use """triple double quotes"""
D400 EndsInPeriod First line should end with a period
D402 NoSignature First line should not be the function's signature
D403 FirstLineCapitalized First word of the first line should be properly capitalized
D404 NoThisPrefix First word of the docstring should not be 'This'
D405 CapitalizeSectionName Section name should be properly capitalized ("returns") πŸ› 
D406 NewLineAfterSectionName Section name should end with a newline ("Returns") πŸ› 
D407 DashedUnderlineAfterSection Missing dashed underline after section ("Returns") πŸ› 
D408 SectionUnderlineAfterName Section underline should be in the line following the section's name ("Returns") πŸ› 
D409 SectionUnderlineMatchesSectionLength Section underline should match the length of its name ("Returns") πŸ› 
D410 BlankLineAfterSection Missing blank line after section ("Returns") πŸ› 
D411 BlankLineBeforeSection Missing blank line before section ("Returns") πŸ› 
D412 NoBlankLinesBetweenHeaderAndContent No blank lines allowed between a section header and its content ("Returns") πŸ› 
D413 BlankLineAfterLastSection Missing blank line after last section ("Returns") πŸ› 
D414 NonEmptySection Section has no content ("Returns")
D415 EndsInPunctuation First line should end with a period, question mark, or exclamation point
D416 SectionNameEndsInColon Section name should end with a colon ("Returns") πŸ› 
D417 DocumentAllArguments Missing argument descriptions in the docstring: x, y
D418 SkipDocstring Function decorated with @overload shouldn't contain a docstring
D419 NonEmpty Docstring is empty


For more, see pyupgrade on PyPI.

Code Name Message Fix
U001 UselessMetaclassType __metaclass__ = type is implied πŸ› 
U002 UnnecessaryAbspath abspath(__file__) is unnecessary in Python 3.9 and later πŸ› 
U003 TypeOfPrimitive Use str instead of type(...) πŸ› 
U004 UselessObjectInheritance Class ... inherits from object πŸ› 
U005 DeprecatedUnittestAlias assertEquals is deprecated, use assertEqual instead πŸ› 
U006 UsePEP585Annotation Use list instead of List for type annotations πŸ› 
U007 UsePEP604Annotation Use `X \ Y` for type annotations
U008 SuperCallWithParameters Use super() instead of super(__class__, self) πŸ› 
U009 PEP3120UnnecessaryCodingComment utf-8 encoding declaration is unnecessary πŸ› 
U010 UnnecessaryFutureImport Unnessary future import ... for target Python version


For more, see pep8-naming on PyPI.

Code Name Message Fix
N801 InvalidClassName Class name ... should use CapWords convention
N802 InvalidFunctionName Function name ... should be lowercase
N803 InvalidArgumentName Argument name ... should be lowercase
N804 InvalidFirstArgumentNameForClassMethod First argument of a class method should be named cls
N805 InvalidFirstArgumentNameForMethod First argument of a method should be named self
N806 NonLowercaseVariableInFunction Variable ... in function should be lowercase
N807 DunderFunctionName Function name should not start and end with __
N811 ConstantImportedAsNonConstant Constant ... imported as non-constant ...
N812 LowercaseImportedAsNonLowercase Lowercase ... imported as non-lowercase ...
N813 CamelcaseImportedAsLowercase Camelcase ... imported as lowercase ...
N814 CamelcaseImportedAsConstant Camelcase ... imported as constant ...
N815 MixedCaseVariableInClassScope Variable mixedCase in class scope should not be mixedCase
N816 MixedCaseVariableInGlobalScope Variable mixedCase in global scope should not be mixedCase
N817 CamelcaseImportedAsAcronym Camelcase ... imported as acronym ...
N818 ErrorSuffixOnExceptionName Exception name ... should be named with an Error suffix


For more, see flake8-comprehensions on PyPI.

Code Name Message Fix
C400 UnnecessaryGeneratorList Unnecessary generator (rewrite as a list comprehension) πŸ› 
C401 UnnecessaryGeneratorSet Unnecessary generator (rewrite as a set comprehension) πŸ› 
C402 UnnecessaryGeneratorDict Unnecessary generator (rewrite as a dict comprehension) πŸ› 
C403 UnnecessaryListComprehensionSet Unnecessary list comprehension (rewrite as a set comprehension) πŸ› 
C404 UnnecessaryListComprehensionDict Unnecessary list comprehension (rewrite as a dict comprehension) πŸ› 
C405 UnnecessaryLiteralSet Unnecessary `(list\ tuple)literal (rewrite as aset` literal)
C406 UnnecessaryLiteralDict Unnecessary `(list\ tuple)literal (rewrite as adict` literal)
C408 UnnecessaryCollectionCall Unnecessary `(dict\ list\
C409 UnnecessaryLiteralWithinTupleCall Unnecessary `(list\ tuple)literal passed totuple()(remove the outer call totuple()`)
C410 UnnecessaryLiteralWithinListCall Unnecessary `(list\ tuple)literal passed tolist()(rewrite as alist` literal)
C411 UnnecessaryListCall Unnecessary list call (remove the outer call to list()) πŸ› 
C413 UnnecessaryCallAroundSorted Unnecessary `(list\ reversed)call aroundsorted()`
C414 UnnecessaryDoubleCastOrProcess Unnecessary `(list\ reversed\
C415 UnnecessarySubscriptReversal Unnecessary subscript reversal of iterable within `(reversed\ set\
C416 UnnecessaryComprehension Unnecessary `(list\ set)comprehension (rewrite using(list\
C417 UnnecessaryMap Unnecessary map usage (rewrite using a `(list\ set\


For more, see flake8-bugbear on PyPI.

Code Name Message Fix
B002 UnaryPrefixIncrement Python does not support the unary prefix increment.
B003 AssignmentToOsEnviron Assigning to os.environ doesn't clear the environment.
B004 UnreliableCallableCheck Using hasattr(x, '__call__') to test if x is callable is unreliable. Use callable(x) for consistent results.
B005 StripWithMultiCharacters Using .strip() with multi-character strings is misleading the reader.
B006 MutableArgumentDefault Do not use mutable data structures for argument defaults.
B007 UnusedLoopControlVariable Loop control variable i not used within the loop body. πŸ› 
B008 FunctionCallArgumentDefault Do not perform function calls in argument defaults.
B011 DoNotAssertFalse Do not assert False (python -O removes these calls), raise AssertionError() πŸ› 
B013 RedundantTupleInExceptionHandler A length-one tuple literal is redundant. Write except ValueError: instead of except (ValueError,):.
B014 DuplicateHandlerException Exception handler with duplicate exception: ValueError πŸ› 
B015 UselessComparison Pointless comparison. This comparison does nothing but waste CPU instructions. Either prepend assert or remove it.
B016 CannotRaiseLiteral Cannot raise a literal. Did you intend to return it or raise an Exception?
B017 NoAssertRaisesException assertRaises(Exception): should be considered evil.
B018 UselessExpression Found useless expression. Either assign it to a variable or remove it.
B025 DuplicateTryBlockException try-except block with duplicate exception Exception


For more, see flake8-builtins on PyPI.

Code Name Message Fix
A001 BuiltinVariableShadowing Variable ... is shadowing a python builtin
A002 BuiltinArgumentShadowing Argument ... is shadowing a python builtin
A003 BuiltinAttributeShadowing Class attribute ... is shadowing a python builtin


For more, see flake8-print on PyPI.

Code Name Message Fix
T201 PrintFound print found πŸ› 
T203 PPrintFound pprint found πŸ› 


For more, see flake8-quotes on PyPI.

Code Name Message Fix
Q000 BadQuotesInlineString Single quotes found but double quotes preferred
Q001 BadQuotesMultilineString Single quote multiline found but double quotes preferred
Q002 BadQuotesDocstring Single quote docstring found but double quotes preferred
Q003 AvoidQuoteEscape Change outer quotes to avoid escaping inner quotes


For more, see flake8-annotations on PyPI.

Code Name Message Fix
ANN001 MissingTypeFunctionArgument Missing type annotation for function argument ...
ANN002 MissingTypeArgs Missing type annotation for *...
ANN003 MissingTypeKwargs Missing type annotation for **...
ANN101 MissingTypeSelf Missing type annotation for ... in method
ANN102 MissingTypeCls Missing type annotation for ... in classmethod
ANN201 MissingReturnTypePublicFunction Missing return type annotation for public function ...
ANN202 MissingReturnTypePrivateFunction Missing return type annotation for private function ...
ANN204 MissingReturnTypeMagicMethod Missing return type annotation for magic method ...
ANN205 MissingReturnTypeStaticMethod Missing return type annotation for staticmethod ...
ANN206 MissingReturnTypeClassMethod Missing return type annotation for classmethod ...
ANN401 DynamicallyTypedExpression Dynamically typed expressions (typing.Any) are disallowed in ...

Ruff-specific rules

Code Name Message Fix
RUF001 AmbiguousUnicodeCharacterString String contains ambiguous unicode character '𝐁' (did you mean 'B'?) πŸ› 
RUF002 AmbiguousUnicodeCharacterDocstring Docstring contains ambiguous unicode character '𝐁' (did you mean 'B'?) πŸ› 
RUF003 AmbiguousUnicodeCharacterComment Comment contains ambiguous unicode character '𝐁' (did you mean 'B'?)

Meta rules

Code Name Message Fix
M001 UnusedNOQA Unused noqa directive πŸ› 

<!-- End auto-generated sections. -->

Editor Integrations


Ruff can be installed as an External Tool in PyCharm. Open the Preferences pane, then navigate to "Tools", then "External Tools". From there, add a new tool with the following configuration:

Install Ruff as an External Tool

Ruff should then appear as a runnable action:

Ruff as a runnable action

GitHub Actions

GitHub Actions has everything you need to run Ruff out-of-the-box:

name: CI
on: push
    runs-on: ubuntu-latest
      - uses: actions/checkout@v3
      - name: Install Python
        uses: actions/setup-python@v4
          python-version: "3.10"
      - name: Install dependencies
        run: |
          python -m pip install --upgrade pip
          pip install ruff
      - name: Run Ruff
        run: ruff .


Is Ruff compatible with Black?

Yes. Ruff is compatible with Black out-of-the-box, as long as the line-length setting is consistent between the two.

As a project, Ruff is designed to be used alongside Black and, as such, will defer implementing stylistic lint rules that are obviated by autoformatting.

How does Ruff compare to Flake8?

(Coming from Flake8? Try flake8-to-ruff to automatically convert your existing configuration.)

Ruff can be used as a (near) drop-in replacement for Flake8 when used (1) without or with a small number of plugins, (2) alongside Black, and (3) on Python 3 code.

Under those conditions Ruff is missing 14 rules related to string .format calls, 1 rule related to docstring parsing, and 1 rule related to redefined variables.

Ruff re-implements some of the most popular Flake8 plugins and related code quality tools natively, including:

Beyond rule-set parity, Ruff suffers from the following limitations vis-Γ -vis Flake8:

  1. Ruff does not yet support a few Python 3.9 and 3.10 language features, including structural pattern matching and parenthesized context managers.
  2. Flake8 has a plugin architecture and supports writing custom lint rules. (To date, popular Flake8 plugins have been re-implemented within Ruff directly.)

Which tools does Ruff replace?

Today, Ruff can be used to replace Flake8 when used with any of the following plugins:

Ruff also implements the functionality that you get from yesqa, and a subset of the rules implemented in pyupgrade (12/34).

If you're looking to use Ruff, but rely on an unsupported Flake8 plugin, free to file an Issue.

Do I need to install Rust to use Ruff?

Nope! Ruff is available as ruff on PyPI:

pip install ruff

Ruff ships with wheels for all major platforms, which enables pip to install Ruff without relying on Rust at all.

Can I write my own plugins for Ruff?

Ruff does not yet support third-party plugins, though a plugin system is within-scope for the project. See #283 for more.

Does Ruff support NumPy- or Google-style docstrings?

Yes! To enable a specific docstring convention, start by enabling all pydocstyle error codes, and then selectively disabling based on your preferred convention.

For example, if you're coming from flake8-docstrings, the following configuration is equivalent to --docstring-convention=numpy:

extend-select = ["D"]
extend-ignore = [

Similarly, the following is equivalent to --docstring-convention=google:

extend-select = ["D"]
extend-ignore = [

Similarly, the following is equivalent to --docstring-convention=pep8:

extend-select = ["D"]
extend-ignore = [


Ruff is written in Rust (1.65.0). You'll need to install the Rust toolchain for development.

Assuming you have cargo installed, you can run:

cargo run resources/test/fixtures

For development, we use nightly Rust:

cargo +nightly fmt
cargo +nightly clippy
cargo +nightly test


Ruff is distributed on PyPI, and published via maturin.

See: .github/workflows/release.yaml.


First, clone CPython. It's a large and diverse Python codebase, which makes it a good target for benchmarking.

git clone --branch 3.10 https://github.com/python/cpython.git resources/test/cpython

Add this pyproject.toml to the CPython directory:

line-length = 88
extend-exclude = [

Next, to benchmark the release build:

cargo build --release

hyperfine --ignore-failure --warmup 10 --runs 100 \
  "./target/release/ruff ./resources/test/cpython/ --no-cache" \
  "./target/release/ruff ./resources/test/cpython/"

Benchmark 1: ./target/release/ruff ./resources/test/cpython/ --no-cache
  Time (mean Β± Οƒ):     297.4 ms Β±   4.9 ms    [User: 2460.0 ms, System: 67.2 ms]
  Range (min … max):   287.7 ms … 312.1 ms    100 runs

  Warning: Ignoring non-zero exit code.

Benchmark 2: ./target/release/ruff ./resources/test/cpython/
  Time (mean Β± Οƒ):      79.6 ms Β±   7.3 ms    [User: 59.7 ms, System: 356.1 ms]
  Range (min … max):    62.4 ms … 111.2 ms    100 runs

  Warning: Ignoring non-zero exit code.

To benchmark against the ecosystem's existing tools:

hyperfine --ignore-failure --warmup 5 \
  "./target/release/ruff ./resources/test/cpython/ --no-cache" \
  "pylint --recursive=y resources/test/cpython/" \
  "pyflakes resources/test/cpython" \
  "autoflake --recursive --expand-star-imports --remove-all-unused-imports --remove-unused-variables --remove-duplicate-keys resources/test/cpython" \
  "pycodestyle resources/test/cpython" \
  "flake8 resources/test/cpython" \
  "python -m scripts.run_flake8 resources/test/cpython"

In order, these evaluate:

  • Ruff
  • Pylint
  • Pyflakes
  • autoflake
  • pycodestyle
  • Flake8
  • Flake8, with a hack to enable multiprocessing on macOS

(You can poetry install from ./scripts to create a working environment for the above.)

Benchmark 1: ./target/release/ruff ./resources/test/cpython/ --no-cache
  Time (mean Β± Οƒ):     297.9 ms Β±   7.0 ms    [User: 2436.6 ms, System: 65.9 ms]
  Range (min … max):   289.9 ms … 314.6 ms    10 runs

  Warning: Ignoring non-zero exit code.

Benchmark 2: pylint --recursive=y resources/test/cpython/
  Time (mean Β± Οƒ):     37.634 s Β±  0.225 s    [User: 36.728 s, System: 0.853 s]
  Range (min … max):   37.201 s … 38.106 s    10 runs

  Warning: Ignoring non-zero exit code.

Benchmark 3: pyflakes resources/test/cpython
  Time (mean Β± Οƒ):     40.950 s Β±  0.449 s    [User: 40.688 s, System: 0.229 s]
  Range (min … max):   40.348 s … 41.671 s    10 runs

  Warning: Ignoring non-zero exit code.

Benchmark 4: autoflake --recursive --expand-star-imports --remove-all-unused-imports --remove-unused-variables --remove-duplicate-keys resources/test/cpython
  Time (mean Β± Οƒ):     11.562 s Β±  0.160 s    [User: 107.022 s, System: 1.143 s]
  Range (min … max):   11.417 s … 11.917 s    10 runs

Benchmark 5: pycodestyle resources/test/cpython
  Time (mean Β± Οƒ):     67.428 s Β±  0.985 s    [User: 67.199 s, System: 0.203 s]
  Range (min … max):   65.313 s … 68.496 s    10 runs

  Warning: Ignoring non-zero exit code.

Benchmark 6: flake8 resources/test/cpython
  Time (mean Β± Οƒ):     116.099 s Β±  1.178 s    [User: 115.217 s, System: 0.845 s]
  Range (min … max):   114.180 s … 117.724 s    10 runs

  Warning: Ignoring non-zero exit code.

Benchmark 7: python -m scripts.run_flake8 resources/test/cpython
  Time (mean Β± Οƒ):     20.477 s Β±  0.349 s    [User: 142.372 s, System: 1.504 s]
  Range (min … max):   20.107 s … 21.183 s    10 runs

  './target/release/ruff ./resources/test/cpython/ --no-cache' ran
   38.81 Β± 1.05 times faster than 'autoflake --recursive --expand-star-imports --remove-all-unused-imports --remove-unused-variables --remove-duplicate-keys resources/test/cpython'
   68.74 Β± 1.99 times faster than 'python -m scripts.run_flake8 resources/test/cpython'
  126.33 Β± 3.05 times faster than 'pylint --recursive=y resources/test/cpython/'
  137.46 Β± 3.55 times faster than 'pyflakes resources/test/cpython'
  226.35 Β± 6.23 times faster than 'pycodestyle resources/test/cpython'
  389.73 Β± 9.92 times faster than 'flake8 resources/test/cpython'




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*Note that all licence references and agreements mentioned in the Ruff README section above are relevant to that project's source code only.