Text Diff
Compare two text blocks line by line and see exactly what was added, removed or kept.
How to use the Text Diff Checker
A diff shows what changed between two versions of a text. Paste the original on the left and the revised version on the right; the tool finds the longest common line sequence and marks every other line as an addition or a deletion. Everything runs in your browser.
- 01Paste the original text into the left panel.
- 02Paste the changed text into the right panel.
- 03Read the diff: lines prefixed with
+are new, lines prefixed with-were removed, and unmarked lines are unchanged.
tips
- —The diff is line-based. If you change a single word in a line, the whole line shows as both removed and added.
- —For best results, normalise line endings first. Mixed
\r\nand\ncan make matching lines look different. - —The algorithm is fast for a few hundred lines but slows down on thousands \u2014 trim large logs before pasting.
frequently asked
How does the diff work?+
The tool splits both texts into lines and computes the longest common subsequence (LCS). Matching lines stay marked as equal; lines only in the left text are deletions; lines only in the right text are additions.
Does it do word-level or character-level diff?+
No. This tool works at line granularity, which is best for comparing source code, config files or structured text. For word-level changes, copy the two changed lines somewhere finer-grained.
Is there a size limit?+
No hard limit, but the diff algorithm is O(n*m) in memory. For very large inputs (thousands of lines) the browser may slow down. Keep inputs under a few hundred lines for instant feedback.
Is my text sent to a server?+
No. Comparison happens entirely in your browser. Nothing you paste is uploaded.