Text Diff

About this text diff tool

Paste two versions of anything — config files, JSON payloads, log excerpts, prose — and see exactly what changed. The comparison runs entirely in your browser, so you can safely diff production config and API responses that should not be pasted into someone else's server.

How the comparison works

This finds the longest common subsequence between the two texts, which is the same idea behind diff and git diff. That matters because the naive approach — comparing line 1 to line 1, line 2 to line 2 — falls apart the moment a line is inserted near the top: every subsequent line appears changed even though nothing else moved. Finding the true common subsequence keeps the diff minimal, so one inserted line shows as one inserted line.

Modified lines are then compared again word by word, so you can see which words changed rather than just which lines did.

Side by side or inline

Side by side pairs each removed line with its replacement, which is easier for reading edits to prose or config. Inline is the familiar +/- layout from the terminal, and is easier to scan when changes are clustered.

Ignoring whitespace and case

Ignore whitespace collapses runs of spaces and ignores indentation, which is what you want after a reformat has touched every line. Ignore case is useful for comparing things that were normalised differently. Both affect only the comparison — the text shown is always exactly what you pasted.

Exporting the result

Copy or download the result as a unified diff with three lines of context — the standard patch format, so it can be pasted into a code review or applied with git apply.