Diff Checker
Paste two versions of any text — code, config, an article draft — and instantly see what changed. Added lines are highlighted green, removed lines red, and unchanged lines stay neutral.
How it works
The tool splits both texts into lines and computes their longest common subsequence (LCS) with dynamic programming. Lines that fall outside the LCS are reported as removals (from the original) or additions (in the changed text), producing a minimal, easy-to-read line diff.
Frequently asked questions
Is my text uploaded anywhere?
No. The comparison runs entirely in your browser with JavaScript — nothing leaves your device.
Does it ignore whitespace differences?
No, comparison is exact line-by-line. A line that only changed in indentation counts as removed plus added. Trim or format both sides first if you want to ignore whitespace.
Is there a size limit?
There's no hard limit, but the LCS algorithm uses memory proportional to the number of lines in each text. Thousands of lines are fine; entire books may be slow.