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Alex Spinov
Alex Spinov

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Ruff Has a Free API You've Never Heard Of

#ruff #python #linting #tooling

Ruff is a Python linter and formatter written in Rust. It's 10-100x faster than existing tools and can replace Flake8, isort, pyupgrade, and Black — all in one binary.

What Makes Ruff Special?

  • 100x faster — lints entire projects in milliseconds
  • All-in-one — replaces Flake8 + isort + pyupgrade + Black
  • 800+ rules — from Flake8, pycodestyle, pyflakes, and more
  • Auto-fix — fixes most issues automatically
  • Drop-in — same rules you already know

The Hidden API: Programmatic Usage 

import subprocess
import json

# Get lint results as JSON
result = subprocess.run(
    ['ruff', 'check', '--output-format', 'json', 'src/'],
    capture_output=True, text=True
)
diagnostics = json.loads(result.stdout)

for d in diagnostics:
    print(f"{d['filename']}:{d['location']['row']} - {d['code']}: {d['message']}")
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Configuration API 

# pyproject.toml
[tool.ruff]
line-length = 100
target-version = "py312"

[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
    "TCH", # flake8-type-checking
    "RUF", # ruff-specific rules
]
ignore = ["E501"]
fixable = ["ALL"]

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

[tool.ruff.format]
quote-style = "double"
indent-style = "space"
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CLI API 

# Lint
ruff check src/

# Lint with auto-fix
ruff check --fix src/

# Format (replaces Black)
ruff format src/

# Check + format in one command
ruff check --fix src/ && ruff format src/

# Show what would change
ruff format --diff src/

# Pre-commit integration
ruff check --fix --exit-non-zero-on-fix src/
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Quick Start 

pip install ruff
ruff check .         # Lint
ruff format .        # Format
ruff check --fix .   # Auto-fix
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Why Python Teams Switch to Ruff

A developer shared: "Our CI linting step took 3 minutes with Flake8 + isort + Black. Ruff does the same in 0.3 seconds. We also deleted 5 config files and replaced them with 15 lines in pyproject.toml. The migration took 10 minutes."

Optimizing Python workflows? Email spinov001@gmail.com or check my tools.

Still using Flake8 + Black? Give Ruff a try!

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