Does this send my code anywhere?

No. Normalization runs entirely in your browser.

Why doesn't this reindent code like Black does?

In Python, indentation is part of the language's syntax, not just style. Re-deriving indentation from scratch without a real Python parser risks silently changing what your code does. This tool only normalizes existing whitespace (tabs to spaces, trailing spaces, blank line runs) without ever changing a line's relative nesting.

How many spaces does a leading tab become?

Each leading tab character is replaced with 4 spaces. This only applies to a line's leading whitespace; a tab appearing later in a line, such as inside a string literal, is left untouched.

How many consecutive blank lines does it allow?

At most one. Runs of two or more consecutive blank lines are collapsed down to a single blank line, matching what tools like Black also do, though this tool does nothing else Black does.

Python Formatter - Format Python Online

Overview

Introduction

Python code pasted from different editors sometimes mixes tabs and spaces, or carries trailing whitespace and inconsistent blank-line spacing.

This tool cleans up that whitespace without touching indentation depth, entirely in your browser.

What Is Python Formatter?

A whitespace normalizer, not a full Python formatter: it converts leading tabs to 4 spaces (consistently, per line), trims trailing whitespace, and collapses runs of blank lines to at most one.

It deliberately never re-derives indentation from code structure, since in Python that structure is semantically significant.

How Python Formatter Works

Each line's leading tabs are expanded to spaces and trailing whitespace is stripped.

Consecutive blank lines are collapsed to a single blank line, and a single trailing newline is ensured.

When To Use Python Formatter

Use it when a Python snippet has mixed tabs and spaces, or excess blank lines, after being copied from elsewhere.

It's a safe cleanup step precisely because it can't change existing indentation depth.

Often used alongside Ruby Formatter and TOML Formatter.

Features

Advantages

Runs entirely client-side with no Python interpreter required.
Never risks changing program behavior, since it doesn't touch relative indentation.
Cleans up trailing whitespace and excess blank lines in a single pass, with no configuration needed.

Limitations

Doesn't reformat line length, quote style, or spacing around operators the way Black does.
If tabs and spaces were already inconsistently mixed within the same line, this won't reliably fix it.

Examples

Mixed whitespace

Input

def greet(name):   
	return f"Hello, {name}"



print(greet("Ada"))

Output

def greet(name):
    return f"Hello, {name}"

print(greet("Ada"))

Trailing spaces are trimmed, the tab becomes 4 spaces, and the extra blank lines collapse to one.

Best Practices & Notes

Best Practices

For real formatting (line length, string quote style), run Black or a similar tool locally; use this for a quick whitespace cleanup first.
Run this before diffing two versions of a file, so trailing-whitespace and blank-line noise doesn't obscure the real changes.

Developer Notes

Implemented as a pure string transform: per-line trailing-whitespace trim, tab-to-space expansion on leading whitespace only, and blank-line run collapsing. No AST parsing is involved.

Python Formatter Use Cases

Cleaning up a Python snippet copied from a PDF, slide, or chat tool
Fixing mixed tabs/spaces before pasting into an editor that enforces one or the other

Common Mistakes

Expecting this to fix line length, string quoting, or import ordering; those require a real formatter like Black or isort.
Assuming it fixes indentation depth itself; a line indented with the genuinely wrong number of spaces passes through unchanged.

Tips

If indentation still looks wrong after normalizing, check the original source for genuinely inconsistent indentation depth, which this tool intentionally won't alter.
Run the output through a linter like flake8 or ruff afterward to confirm it's still valid Python, since this pass doesn't validate syntax.

Python Formatter