Diff Checker — Compare Text Side by Side
Compare two blocks of text with a line-by-line side-by-side diff
How it works
- 1Paste both versions
Drop the original into the left column and the changed version into the right.
- 2Read the diff
Additions highlight green on the right, removals highlight red on the left, line numbers on both sides.
- 3Toggle whitespace
Enable 'Ignore whitespace' to hide trailing-space or indentation-only diffs.
About Diff Checker — Compare Text Side by Side
Free online diff checker. Paste two blocks of text to see a side-by-side line diff — additions in green, removals in red, with line numbers. Optional ignore-whitespace mode. Runs entirely in your browser. Diff Checker — Compare Text Side by Side on 712 Tools runs entirely inside your browser using modern JavaScript APIs — no server ever sees your data. That means instant results, complete privacy, and no upload limits.
Whether you need to compare two blocks of text with a line-by-line side-by-side diff for a debugging session, a quick sanity check, or a production incident, this tool is free to use as many times as you need. There are no watermarks, no sign-up, and no ads inside the tool itself.
Frequently asked questions
What algorithm is used?
A longest-common-subsequence (LCS) diff, the same approach used by git diff. Runs entirely in the browser.
Is there a size limit?
The LCS algorithm is O(n·m) in memory. Very large diffs (10,000+ lines) may slow the browser.
Are my texts uploaded?
Never. Both blocks stay in your browser — nothing is sent to any server.
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