Text Diff Checker
Paste two versions of a text and see exactly which lines were added, removed or left unchanged, side by side. The comparison runs entirely in your browser.
- Runs entirely in your browser
- No sign-up, no watermark
- Free and unlimited
🔒 Your file stays on your device
How to use Text Diff Checker
- 1
Open Text Diff Checker and paste the original text on the left.
- 2
Paste the changed version on the right.
- 3
The line-by-line differences appear below as you type — added lines in green, removed in red.
- 4
Copy the unified diff if you need it elsewhere.
What you get
- Line-level diff with added / removed highlighting
- Live — updates as you type
- Copy a unified diff
- Runs entirely in the browser
What happens to your files
This tool runs entirely in your browser. The file you choose is read into memory, processed on your device, and offered back as a download. Nothing is uploaded and nothing is kept once you leave the page.
There is no account, no email, no watermark and no daily limit. Come back whenever you need it.
Frequently asked questions
- Is this a character-level or line-level diff?
- Line-level. Each line is compared as a whole using a longest-common-subsequence match, which is the most useful view for code and prose.
- Are my texts uploaded?
- No. The comparison is pure JavaScript running on your device — nothing is sent anywhere.