Text Diff Checker
Compare two blocks of text and highlight added, removed and changed lines.
Enter text in both boxes to see a diff.
Spot every change at a glance
The Text Diff Checker compares two blocks of text and highlights the differences line-by-line. Paste an original version in the left panel and the updated version in the right panel — the color-coded output below shows exactly what was added, removed, or left alone.
What’s a “diff”?
A diff is a compact summary of changes between two versions of text. Engineers use diffs every day to review code; writers and editors use them to track revisions; sysadmins use them to spot changes in logs and configs. Our checker uses the same algorithm (Myers’ diff) that powers git diff and most other version control tools.
Common uses
- Proofreading — compare an edited draft to the original and confirm every intended change made it in.
- Configuration review — diff a working config file against a broken one to find the offending line.
- Changelog authoring — quickly see what moved between two release notes drafts.
- Content moderation — check whether a user’s edit introduced meaningful changes or just formatting.
Privacy
Both text boxes stay in your browser’s memory. No text is ever uploaded, logged, or persisted. You can paste a confidential document and close the tab — the content is gone.
Frequently asked questions
- Does the diff go character-by-character or line-by-line?
- This checker compares text line-by-line, which is the right granularity for most real-world comparisons — prose drafts, configuration files, logs, changelogs. Character-level diffs are noisier than they are useful.
- What does "+3 lines added" mean?
- Lines that exist in the new text but not in the original are counted as added. Lines that existed in the original but not in the new text are counted as removed. Lines present in both are unchanged.
- Is there a limit on how much text I can compare?
- There is no artificial limit. Both blocks live in your browser's memory. Very large files (megabytes of text) may be slow to diff interactively, but hundreds of kilobytes work comfortably.