Free Diff Checker (Text Compare)

Paste two versions of a text to see added, removed, and changed lines side by side — with word-level highlights.

Original
Changed
+2 added−1 removed
Differences
1−The quick brown fox
1+The quick red fox
22jumps over the lazy dog.
3+Hello there.
34Goodbye.

How to use / FAQ

Paste an original text on the left and a changed version on the right to see exactly what differs. Removed lines are shown in red, added lines in green, and unchanged lines in gray. When a line is edited rather than replaced, the specific words that changed are highlighted so you can spot small edits at a glance.

What can I compare with a diff checker?

Anything text-based: two drafts of an article, versions of a config file, code snippets, contract clauses, or JSON payloads. It works line by line, so it's ideal for spotting exactly what changed between two revisions.

How does the line comparison work?

It uses a longest-common-subsequence algorithm — the same technique behind git and other diff tools — to find the smallest set of additions and deletions that turns the original into the changed text. Matching lines stay aligned so real changes stand out.

What do the colors and word highlights mean?

Red marks lines removed from the original, green marks lines added in the changed version, and gray marks lines that are the same. Inside a modified line, the exact added or removed words get a brighter highlight.

Is my text uploaded to compare it?

No. The comparison runs entirely in your browser, so confidential documents, code, or data never leave your device.