Text Diff Checker

Line by line. Each line in Text A is matched against the lines in Text B, so if even one word changes, the entire line is marked as removed and its replacement as added — it won't underline just the changed word within a line.

A green line with a + means that line was added in Text B and wasn't present in Text A. A red line with a - means that line existed in Text A but was removed in Text B. Lines with no symbol and no highlight are unchanged and appear in both.

Common uses include comparing two versions of code before committing a change, spotting what changed between two config files, reviewing edits between drafts of an article, and redlining changes between versions of a contract or legal document.

It's a similar approach. This tool finds the longest common subsequence (LCS) between the two texts to work out the minimal set of line additions and removals — the same general family of algorithm that git and most diff tools use under the hood.

Yes. The comparison runs entirely in your browser using JavaScript — nothing you paste is uploaded, transmitted, or stored anywhere. You can safely compare private code, contracts, or drafts.