Text Diff Checker
Compare two texts side by side, highlight added and removed lines, and see a similarity score. Free online text diff checker — runs in your browser.
Original
Modified
About the Text Diff Checker
Compare two blocks of text side by side or inline, with added, removed, and modified lines highlighted and a similarity score computed automatically. It works for essays, code, config files, JSON, contracts — anything where you need to spot what changed.
Everything runs entirely in your browser — nothing is sent to a server. Your text never leaves your device, so you can safely compare private documents, source code, or confidential data.
Common use cases
- Review edits between two drafts of an article, email, or contract.
- Spot changes between two versions of a config file or code snippet.
- Check what a collaborator changed before merging their text back in.
- Verify that a copy-paste or migration preserved the original content.
How it works
- Paste or upload your original text on the left and the modified text on the right.
- Changes highlight instantly — red for removed, green for added, yellow for modified.
- Read the similarity score and switch between side-by-side and inline views.
- Copy the diff or export it as HTML, Markdown, or JSON.
Frequently asked questions
Is my text uploaded to a server?
No. The diff is computed entirely in your browser — nothing is sent to a server, so your content stays private.
What does the similarity percentage mean?
It estimates how much of the two texts is identical, based on matching content between them.
Can I export the comparison?
Yes. You can export the highlighted diff for sharing or record-keeping.
Is there a size limit?
There is no hard limit, though very large inputs may take longer since everything runs locally.