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What is Ruff?

Ruff is a modern Python tool that’s incredibly fast and combines multiple tools in one:
  • Linting - Finding issues and potential errors
  • Formatting - Fixing code style automatically
  • Import sorting - Organizing imports cleanly
It’s beginner-friendly with clear error messages and works seamlessly with VS Code.
A linter checks your code for style issues and potential errors. A formatter automatically fixes these issues for you.

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Install Ruff in VS Code

  1. Open VS Code
  2. Press Ctrl+Shift+X (Windows/Linux) or Cmd+Shift+X (Mac)
  3. Search for “Ruff”
  4. Install the official Ruff extension by Astral
The Ruff extension replaces older tools like Pylint, Black, and isort. You only need this one extension.

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Enable format on save

Let’s make VS Code automatically format your code when you save:
  1. Press Ctrl+, (Windows/Linux) or Cmd+, (Mac) to open settings
  2. Search for “format on save”
  3. Check the box for “Editor: Format On Save”
  4. Search for “default formatter”
  5. Set “Python > Formatting: Provider” to “Ruff”

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See it in action

Here’s messy code before formatting: 
import os
def   calculate_total(items):
    total=0
    for item in items:
        total+=item['price']*item['quantity']
    return total

shopping_cart=[{'name':'apple','price':0.5,'quantity':6},{'name':'banana','price':0.3,'quantity':8}]
print(calculate_total(shopping_cart))
After saving with Ruff (automatic): 
import os


def calculate_total(items):
    total = 0
    for item in items:
        total += item["price"] * item["quantity"]
    return total


shopping_cart = [
    {"name": "apple", "price": 0.5, "quantity": 6},
    {"name": "banana", "price": 0.3, "quantity": 8},
]
print(calculate_total(shopping_cart))
Ruff automatically:
  • Separated imports
  • Added proper spacing
  • Fixed indentation
  • Made quotes consistent
  • Formatted the list for readability
If formatting doesn’t work on save, right-click in your Python file and select “Format Document”. This should trigger Ruff manually.

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Common formatting rules

Ruff follows Python’s style guide (PEP 8) automatically:
  • 4 spaces for indentation
  • Spaces around operators (x = 1, not x=1)
  • Two blank lines between functions
  • Maximum line length of 88 characters
You don’t need to memorize these - Ruff handles them for you!

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Understanding linting errors

Ruff will underline code issues in your editor: 
# Unused imports (Ruff warns you)
import os
import sys

# Only using one
print("Hello")
Hover over underlined code to see:
  • What the issue is
  • Why it matters
  • How to fix it
Don’t ignore linting warnings! They help you write better code and catch bugs early.

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What’s next?

With Ruff set up, your code will always look professional and follow best practices automatically.