Free Diff Checker — Compare Texts Online
Our Diff Checker helps you compare two versions of text, code, or documents and see exactly what changed. Additions are highlighted in green, removals in red. Line numbers make it easy to locate specific changes. Works with code files, configuration changes, document revisions, and any plain text.
Powered by a pure JavaScript diff algorithm — all comparison happens in your browser. No text is sent to any server, making this safe for confidential code and sensitive documents.
Last Updated: April 2026
Frequently Asked Questions
A diff checker compares two texts and outputs the differences. Lines that exist only in the original are marked as removed (red). Lines that exist only in the changed version are marked as added (green). Lines present in both are shown unchanged. This is the same algorithm used by git diff, SVN, and other version control systems.
Yes. The diff checker treats any text as plain text — it works equally well with source code, configuration files, markdown, SQL, and prose. Just paste the two versions into the input boxes.
Completely. All comparison happens in your browser using JavaScript. Nothing is transmitted to our servers. You can safely paste confidential code, database queries, and sensitive configurations.
Line diff compares entire lines — a line is either added, removed, or unchanged. Word diff highlights individual words within changed lines, showing more granular changes. Use line diff for code and word diff for prose documents where paragraphs change slightly.