Prompt diff checker
Changed a prompt and the answers changed too? Paste both versions to see exactly which words moved, so you know what made the difference.
Free tool · Updated
Changes
Paste both versions and the changes show here.
How to use it
- Paste the old prompt on the left and the new one on the right, or tap Try an example.
- Pick Words for small edits, or Lines for long prompts.
- Read the changes: red was removed, green was added.
Tips
- Change one thing at a time when testing prompts. A diff makes it easy to check you did.
- Watch the token count. A small edit can add a lot of tokens, and cost, at scale.
- Keep each version you test, with a note on what it did better.
- Use Lines mode for system prompts and long templates.
Frequently asked questions
What is a prompt diff?
A side-by-side comparison that shows exactly what changed between two versions of a prompt, word by word or line by line.
Does it work for any text?
Yes. Prompts, emails, code or any two texts.
How are tokens counted?
As an estimate of about 4 characters per token for English, close to what most models use. Exact counts differ a little between models.
Is my text sent anywhere?
No. The comparison runs in your browser.
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