Text Diff
Compare two texts side-by-side and see a line-by-line diff with additions and removals highlighted — instant, in your browser.
100% in your browser
No watermark
No sign-up
How it works
- Paste your original text into the left box and the modified text into the right box.
- The diff is computed live in your browser as you type — no server involved.
- Removed lines are highlighted in red (prefixed with −), added lines in green (+), and unchanged lines are plain.
- Click "Copy diff" to copy the unified diff to your clipboard.
Frequently asked questions
- How does the comparison work?
- The tool runs a Longest Common Subsequence (LCS) algorithm on the lines of both texts, the same approach used by standard diff utilities. It finds the minimal set of additions and removals needed to turn the original into the modified text.
- Is my text uploaded anywhere?
- No. Everything runs locally in your browser using JavaScript. Your text never leaves your device.
- What does the Copy diff button produce?
- It copies a plain-text unified diff where each line is prefixed with +, - or a space, which you can paste into any editor or bug report.