#134 · Programming Languages Developer Tool

Python Validator

Check Python code for unmatched delimiters, indentation inconsistencies, missing colons, risky patterns, and common style problems. All checks run locally in the browser and produce line-based errors, warnings, and suggested fixes.

Developer Input

Source code

Python Validator Input

def greet(name)
    print("Hello", name)

def load(items=[]):
    try:
        return items[0]
    except:
        pass

Report Format

Maximum Line Length

chars

Check indentation Check brackets and quotes Check risky patterns Auto-fix safe whitespace Include passed checks Auto-run while typing

How to use this developer tool

Paste Python code.
Choose a readable, JSON, or safe-fix result.
Set the preferred maximum line length.
Run validation.
Review line-based findings and verify with Python.

What this developer tool does

It combines delimiter matching, indentation checks, declaration heuristics, and lint-style pattern detection. Safe fixes are limited to whitespace and final-newline cleanup.

Mask strings and comments → match delimiters → inspect indentation → test declaration patterns → detect risk rules → build report.

This validator does not run Python or replace py_compile, Ruff, Flake8, or an IDE parser.

Example

Input

def test()
    print("Hello")

Result

ERROR PY001 line 1: Missing colon after function declaration.

Tips for better output

Treat Errors as likely syntax or structure problems.
Review Warnings before applying code changes.
Use a Python interpreter for authoritative validation.

FAQ

How do I check Python syntax errors online?

Paste the code and run the validator for structural and common syntax heuristics.

How can I find mixed tabs and spaces in Python?

Enable indentation checks. Lines with mixed leading indentation are reported.

How do I detect missing colons in Python code?

The validator checks common block declarations such as def, class, if, for, and while.

Can I automatically fix indentation errors in Python?

Only safe whitespace cleanup is automated. Semantic indentation changes require manual review.

Why does valid Python code still show a browser validation warning?

The validator uses static heuristics and may flag unusual but valid syntax. Confirm with Python itself.

Related developer tools

TypeScript Checker TypeScript Generator TypeScript Formatter TypeScript Converter

Severity model

Error	Likely structural failure
Warning	Risk or maintainability issue
Notice	Style or review item
Passed	No issue for the checked rule

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