Compare text online to find the difference between two text files.
Compare two texts and highlight differences online, free. A diff checker compares two pieces of text and highlights exactly what was added, removed, or changed between them. This tool runs the comparison in your browser and marks the differences inline, so you can review edits, config changes, or code revisions without uploading anything.
Differences are computed locally and shown with clear add/remove highlighting, so you can spot every change at a glance — even in large blocks of text. 100% free, no registration, and complete privacy — everything runs locally in your browser, so your data never touches a server.
Inserted and deleted text are color-coded so changes between the two inputs are immediately visible.
Compare two versions side by side to review edits in code, config, or documents.
The diff is computed client-side as you paste — no upload, no wait, works offline.
Both texts stay in your browser and are never uploaded — safe for proprietary code or sensitive documents.
It aligns the two inputs and finds the smallest set of insertions and deletions that turns the first into the second (the basis of the classic Myers diff algorithm), then highlights those changes so you can see exactly what differs.
Yes. It works on any plain text, including source code, JSON, YAML, and config files. Because it runs in your browser, you can safely diff proprietary code without it leaving your machine.
It highlights changed regions between the two inputs so you can see added and removed content. For the cleanest results, paste comparable versions (e.g. before/after of the same file).
There's no fixed limit beyond your device's memory, since everything runs locally. Very large inputs may take a moment to render the highlighted diff.
No. Both inputs are compared entirely in your browser and are never sent to a server.