CodeUtility
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AI for Python

Python Code Checker and Fixer

Paste Python code and choose Check and fix to find syntax errors, exceptions and logic bugs, with a corrected version and an explanation of each change. Choose Explain code to have it explained line by line. Then run the result in the online Python editor.

Check your Python code

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Try an example:

How to check and fix Python code

  1. Paste your Python code into the box, including the error message as a comment if you have one.
  2. Select Check and fix to find bugs and get a corrected version, or Explain code to understand what it does.
  3. Read the explanation. For a fix, it says what was wrong and why the change solves it.
  4. Select Open in editor to run the fixed code in the online Python compiler and confirm it works.

Python errors it finds and explains

  • SyntaxError and IndentationErrorMissing colons, brackets and quotes, mixed tabs and spaces, and code at the wrong indentation level.
  • TypeError and ValueErrorAdding a string to a number, forgetting int() around input(), and calling a function with the wrong arguments.
  • IndexError, KeyError and NameErrorLoops that go one step too far, missing dictionary keys, and misspelled or undefined names.
  • Logic bugsrange() that skips the first item, integer division where you wanted decimals, mutable default arguments and conditions that are always true.

Frequently asked questions

How does the Python code checker work?

Paste your code and choose Check and fix. The AI reads it, explains each problem it finds, such as a syntax error, an off-by-one loop or a wrong type, and returns a corrected version you can run.

Can it explain Python code?

Yes. Choose Explain code to get a plain-language walkthrough of what the code does, which helps with homework, code reviews and unfamiliar scripts.

Is the fixed code tested?

Not automatically. Select Open in editor to run the fixed code in the online Python compiler and check the result yourself.

Is it free?

Yes, with a free account and a daily AI token quota.

Does it check style (PEP 8)?

It points out clear style problems while explaining, but it focuses on bugs and errors. For strict PEP 8 checks, use a linter such as flake8 or ruff.