Diff Checker: compare two texts
Compare two texts or files and see exactly what changed, line by line and word by word. Side by side or unified view. Free, nothing uploaded.
Original
Changed
What this tool is for
Paste two versions and see what moved between them: added lines in green, removed in red, and inside a changed line the exact words that differ. Useful for contracts, configuration files, translations and anything else where the difference matters more than the text itself. Both versions stay in your browser, which is the point when the document is not public.
How to use it
- Paste the original on the left and the changed version on the right.
- Read the result: added, removed and changed lines are coloured, and words inside changed lines are highlighted.
- Switch to unified view if you prefer the format that patches use.
- Turn on ignore case or ignore whitespace when those differences are noise.
Frequently asked questions
What is the difference between side by side and unified?
Side by side puts the versions in two columns, which reads better for prose. Unified stacks removals and additions in one column with minus and plus signs, which is what git and code review tools show.
Why is a line marked as changed rather than added and removed?
When a removal and an addition line up, the tool treats them as one edit and shows the words that differ. That is almost always what happened, and it is far easier to read than two separate lines.
Can I compare files?
Open the files and paste their contents. Nothing is uploaded either way: the comparison runs in your browser, so confidential documents stay on your machine.
How large a text can it handle?
Comfortably into the thousands of lines. The comparison uses the Hunt-Szymanski algorithm rather than a full distance matrix, so memory grows with the number of matching lines and not with the square of the length.