Text Diff Checker
Compare two texts and see exactly what changed — additions, removals, and word-level detail within changed lines. Your text never leaves your browser.
Compared locally. Your text never leaves your browser.
Paste text into both boxes to see a comparison.
How it works
This tool compares your two texts line by line, finding the shortest set of line insertions and deletions that turns the first text into the second — the same class of algorithm used by tools like Git and diff. It also highlights word-level changes within a replaced line, but only when a block of removed lines lines up one-to-one with the added lines replacing it (for example, two lines replaced by two lines). A block where the counts don't match — say, two lines replaced by three — is shown as a plain removal and addition without word-level highlights, since there's no unambiguous way to pair up which added line corresponds to which removed one. Line-ending style (Windows CRLF vs. Unix LF) and a single trailing newline at the end of a file are ignored, since they don't represent an actual content difference.
Common questions
Is there a limit on how much text I can compare?
Combined input is capped at around 5 million characters. Separately, if the two texts are so different from each other that finding an exact diff would be too slow, you'll see a message asking you to compare smaller sections — this is based on how different the texts are, not their raw size, so two large-but-similar documents compare fine while two huge, unrelated ones may hit this.
Does it compare characters, words, or whole lines?
Lines first: each line is marked as kept, added, or removed. Word-level highlighting inside a changed line is a secondary step described below, not a full character-by-character diff of the entire text.