Python Formatter

What Does This Tool Do?

It normalizes indentation in Python source code to a consistent width, making code that mixes tabs and spaces (or inconsistent indent levels from copy-pasting) readable and consistent again.

Why Use This Tool?

Since Python uses indentation to define code blocks, inconsistent spacing isn't just an aesthetic issue - mixed tabs/spaces can cause actual IndentationErrors. This tool normalizes it safely.

How to Use It

1. Paste your Python code.
2. Click Format.
3. Copy the consistently-indented result.

Limitations

This tool never executes your Python code - it only re-indents based on the existing block structure it detects; it cannot fix genuinely broken/ambiguous indentation where the original structure can't be determined.

Example

Code that mixes 2-space and tab indentation, often from copy-pasting:

def greet(names):
  for n in names:
	  print("Hello", n)

is normalised to consistent 4-space levels:

def greet(names):
    for n in names:
        print("Hello", n)

Errors This Prevents

• TabError: inconsistent use of tabs and spaces in indentation
• IndentationError: unexpected indent
• IndentationError: unindent does not match any outer indentation level

These are common when code is pasted from websites, chat apps or PDFs, which often convert indentation unpredictably.

For Projects: Black or Ruff

PEP 8 recommends 4 spaces per level. For full formatting - line length, quotes, spacing - use Black or Ruff:

pip install ruff
ruff format .

Add it as a pre-commit hook and style never needs discussing again. Configure it in pyproject.toml.

Related tools: Python Requirements Generator, JSON to Python and the Code Indentation Tool.