Text Diff Checker
Compare two texts and highlight added, removed and changed parts.
Loading tool…
How to use it
- Paste the original text in box A and the modified version in box B — the diff updates live.
- Added lines are marked with +, removed lines with -, unchanged lines are neutral.
- With word-level highlighting enabled, changed lines also show which words actually changed.
- The summary counts added, removed and unchanged lines.
About this tool
Aligns two versions line by line and highlights insertions, deletions and modifications, with optional word-level granularity inside changed lines. Based on a classic longest-common-subsequence algorithm running locally, with a note on practical size limits.
Your input never leaves the browser: this tool works entirely offline once the page has loaded.
Frequently asked questions
How large can the texts be?
The algorithm needs about n×m comparison cells for n and m lines. Beyond roughly 25 million cells the tool refuses with a clear message instead of freezing the tab.
What do the colors and markers mean?
Lines starting with + were added in B, lines starting with − were removed from the original, and neutral lines are unchanged. Word-level highlighting marks the exact changed words inside paired lines.