Free Online Text Diff Checker

A text diff checker compares two versions of a document and shows you exactly what changed between them. This tool works line by line: it finds the longest common subsequence of lines shared by both inputs, then marks the rest as added (present only in the changed text) or removed (present only in the original). Added lines are highlighted in green, removed lines in red, and unchanged lines stay neutral so the edits stand out. It is useful well beyond code. Compare two drafts of an article, two versions of a contract, configuration files before and after an edit, exported data, or translation strings. The "Ignore case" option treats upper- and lower-case as equal, and "Trim line whitespace" ignores leading and trailing spaces — both are handy when the only differences are cosmetic. Like every tool here, the comparison runs entirely in your browser. Neither block of text is uploaded, so you can safely diff confidential documents, credentials, or internal config without anything leaving your device.