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Alex Spinov
Alex Spinov

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Ruff Has a Free API — The Python Linter That's 100x Faster Than Flake8

#python #ruff #linting #devtools

TL;DR

Ruff is a Python linter and formatter written in Rust that replaces Flake8, isort, Black, pyupgrade, and dozens more tools — all in one binary. It's 10-100x faster and supports 800+ lint rules.

What Is Ruff?

Ruff by Astral is the new standard for Python tooling:

  • 100x faster — written in Rust, lints in milliseconds
  • Drop-in replacement — for Flake8, isort, Black, pyupgrade, pydocstyle
  • 800+ rules — the most comprehensive Python linter
  • Auto-fix — automatically fixes most issues
  • Built-in formatter — Black-compatible, 100x faster
  • Free — MIT license

Quick Start 

# Install
pip install ruff

# Lint
ruff check .

# Lint and auto-fix
ruff check --fix .

# Format (like Black, but faster)
ruff format .
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Configuration 

# pyproject.toml
[tool.ruff]
target-version = "py312"
line-length = 88

[tool.ruff.lint]
select = [
    "E",   # pycodestyle errors
    "W",   # pycodestyle warnings
    "F",   # pyflakes
    "I",   # isort
    "N",   # pep8-naming
    "UP",  # pyupgrade
    "B",   # flake8-bugbear
    "SIM", # flake8-simplify
    "C4",  # flake8-comprehensions
    "DTZ", # flake8-datetimez
    "RUF", # Ruff-specific rules
]
ignore = ["E501"]  # line too long (handled by formatter)

[tool.ruff.lint.isort]
known-first-party = ["mypackage"]

[tool.ruff.format]
quote-style = "double"
indent-style = "space"
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What Ruff Replaces

Old Tool Ruff Equivalent Rules
Flake8 E, W, F pycodestyle + pyflakes
isort I import sorting
Black ruff format code formatting
pyupgrade UP Python version upgrades
pydocstyle D docstring conventions
flake8-bugbear B common bugs
flake8-simplify SIM code simplification
flake8-comprehensions C4 better comprehensions
autoflake F401, F841 unused imports/variables
yesqa RUF100 unused noqa comments

Examples of What Ruff Catches 

# Before ruff --fix
import os
import sys
import os  # duplicate import
from typing import Optional, List

def process(data: Optional[List[str]] = None):
    x = 1  # unused variable
    items = []
    for item in data or []:
        items.append(item.upper())  # use list comprehension

    if len(items) == 0:  # use 'not items'
        return None

    return items
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# After ruff --fix (auto-fixed!)
import sys

def process(data: list[str] | None = None):
    items = [item.upper() for item in data or []]

    if not items:
        return None

    return items
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Pre-commit Hook 

# .pre-commit-config.yaml
repos:
  - repo: https://github.com/astral-sh/ruff-pre-commit
    rev: v0.8.0
    hooks:
      - id: ruff
        args: [--fix]
      - id: ruff-format
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VS Code Integration 

// .vscode/settings.json
{
  "[python]": {
    "editor.formatOnSave": true,
    "editor.defaultFormatter": "charliermarsh.ruff",
    "editor.codeActionsOnSave": {
      "source.fixAll.ruff": "explicit",
      "source.organizeImports.ruff": "explicit"
    }
  }
}
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Speed Comparison

Tool CPython stdlib lint time
Ruff 0.03s
Flake8 12s
Pylint 60s+
pyflakes 3s

Ruff is 400x faster than Flake8 on the CPython codebase.

Resources

Writing Python scrapers? My Apify tools provide production-ready web scraping — all linted with Ruff for clean, fast Python code. Questions? Email spinov001@gmail.com

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