Text Diff Checker

A diff compares two pieces of text line by line and shows what was inserted, deleted or left unchanged — the same idea behind code review and version control. It is the fastest way to spot what changed between two drafts, two config files, or two copied-and-pasted blocks.

This tool computes a line-level diff using a longest-common-subsequence match, so unchanged lines line up and only genuine changes are highlighted. Everything is calculated in your browser — no account, no upload — which makes it safe for comparing private documents, contracts or code.

A diff earns its keep whenever someone says only one thing changed. A client returns a contract claiming a single clause was edited — compare and confirm it. An AI assistant rewrites your copy — see exactly what it touched before accepting. A config file stopped working after an update — line up the old and new versions and the culprit is highlighted in seconds.

Because the comparison works on whole lines, how the text is wrapped matters as much as what it says. Prose that has been rewrapped — one version hard-wrapped at 80 characters, the other in long paragraph lines — shares almost no identical lines, so nearly everything lights up as changed even when the wording is the same. Normalise the two versions to the same wrapping before comparing and the real edits stand out.