Text Compare — Diff Checker
Paste two versions of a text to see precisely what changed. Added lines are marked in green, removed lines in red, and both original and new line numbers are shown so you can locate every change in the source.
How the comparison works
The tool finds the longest common subsequence of lines between the two texts — the same core algorithm behind git diff. Rather than comparing line 1 to line 1 and line 2 to line 2, it identifies the longest run of lines that appear in both versions in the same order, then marks everything else as added or removed. That means inserting a paragraph at the top does not report every subsequent line as changed, which is what naive line-by-line comparison does wrong.
The comparison options
- Ignore case — treats "The" and "the" as identical, so you only see substantive edits.
- Ignore whitespace — collapses runs of spaces and trims line ends before comparing. Essential when one version has been reformatted or re-indented, which otherwise reports every line as changed.
- Show only changes — hides unchanged lines so long documents with a few edits become readable at a glance.
What people compare
Two drafts of a document, to see what an editor actually changed. Two versions of a config file, when one environment works and another does not. Contract revisions, where a single altered clause matters. Code snippets, when you need a quick diff without committing anything. And translated or localised strings against their source. Because everything runs in your browser, you can safely compare confidential documents — neither version is ever uploaded.