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Use cases FAQ

What's the best free AI for writing and debugging code?

Short answer: On the free tier, Claude Sonnet 3.5 is best for explaining and refactoring; ChatGPT 4o is fastest for snippet-level help. Both are strong enough for daily coding.

On the free tier:

  • Claude Sonnet 3.5: best for "read this code and tell me what's wrong" or "refactor this function". Clearer explanations.
  • ChatGPT 4o: fastest for "how do I do X in Python" type questions and bug-fix snippets.

If your codebase is more than a few hundred lines, free-tier models start to struggle with context. Upgrade to Pro for Claude Sonnet 4, its larger context window and stronger reasoning make it a noticeably better pair-programmer.

Pro tip: paste error messages verbatim, not paraphrased. The exact stack trace is the most useful information you can give the AI.

A debugging prompt that consistently works: state the runtime and framework, paste the smallest reproducing snippet, paste the full traceback, then say what you already tried. "Flask + MySQL, this route 500s when user_id is missing, here's the traceback, I already checked the session middleware. Explain the root cause, then show the smallest safe fix." Asking for the explanation before the patch keeps the model honest and teaches you something.

Trust but verify the output: models occasionally hallucinate functions that don't exist, especially for niche libraries or APIs that changed recently. If a suggested method looks unfamiliar, check the docs before hunting for other bugs. And for repetitive coding chores, the site has dedicated programming tools, regex generation, unit tests, commit messages, SQL, that skip the prompt-writing entirely.

A better coding prompt

For coding help, include the goal, the language, the framework, the exact error and the smallest relevant code sample. A strong prompt looks like: I am using Flask and MySQL. This route returns a 500 when user_id is missing. Here is the traceback and route code. Explain the cause, then show the smallest safe fix.

Ask for the reasoning before the patch when you are learning, and ask for only the changed lines when you already understand the code. That keeps answers focused and easier to verify.

How to apply this answer

Copy this template for your next bug: "[Language + version, framework]. Expected: [what should happen]. Actual: [what happens]. Traceback: [paste verbatim]. Code: [smallest reproducing snippet]. I already tried [X]. Explain the root cause first, then show the minimal fix." Fill in the brackets and send.

Related FAQ pages

Try it in a real chatYour first question is free, no signup needed. Ask with your real context, or compare ChatGPT 4o and Claude Sonnet 4 on the same prompt.

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