# Prompt Version Comparator

Compare two versions of a prompt or instruction file and see what changed in the instructions, constraints and output format.

- URL: https://toolstackhub.co.uk/tools/prompt-version-comparator/
- Category: Text Tools
- Price: free, no sign-up
- Privacy: runs in the browser; input is not uploaded
- Last updated: 2026-10-08

## About
Paste an old and a new version of a prompt. The comparator shows the line-by-line differences with added, removed and changed text highlighted, and sorts changes into types: constraints (always, never, must), output format and length, and other instructions. It also reports how much longer or shorter the prompt became. It compares text only; it cannot tell you whether the new version performs better. Test both on real examples.

## How to use
1. Paste or type your input into the box above.
2. Choose any options you need. Results update as you type.
3. Copy the result with the Copy button.

## FAQ
**Does it tell me which prompt is better?** No. It shows what changed. To compare quality, run both prompts on the same set of realistic test inputs and compare the outputs.

**Why does a tiny change matter?** In instructions, "never offer refunds" and "never offer refunds without manager approval" behave differently. The comparator highlights word-level changes inside a line so they are easy to see.

**Is the Prompt Version Comparator free?** Yes, with no sign-up or limits.