Diff Checker

Spot every change at a glance

When you need to know what changed between two versions — a config before and after an edit, two API responses, a pasted snippet versus what's in your editor — reading them side by side is slow and error-prone. This diff checker compares the two texts line by line and shows exactly which lines were added (green) and removed (red), with running counts, so the difference jumps out immediately.

How the comparison works

The diff is computed with a longest-common-subsequence algorithm — the same core idea behind git diff and diff. It finds the largest set of unchanged lines and marks everything else as an insertion or deletion, so moved and edited lines are reported accurately rather than as one giant block of changes. Original and changed line numbers are shown in separate gutters, like a code review.

FAQ

Does it compare word by word or line by line?

Line by line — the most useful granularity for code, configs and logs. If a single line changed, you'll see the whole old line removed and the new line added, which makes the before/after unambiguous.

Can I compare code with different indentation?

Yes, and whitespace is significant — a re-indented line counts as changed, which is usually what you want when reviewing real diffs. Normalize indentation first if you only care about content changes.

Is my text uploaded anywhere?

No — the comparison runs entirely in your browser, so you can diff private configs and source safely. Nothing is transmitted or stored.