Diff Checker
See exactly what changed between two versions.
About this converter
Paste two versions and see what moved. Removed lines are marked with a minus, added lines with a plus, and both line numbers are shown so you can find them in the originals.
Long runs of identical text are collapsed to a … with three lines of context either side, the way a unified diff does. Printing an entire matching file around one changed line is what makes a comparison unreadable.
The comparison is by line, which is the right unit for config files, logs, CSVs and code. Two lines that differ by one character show as one removed and one added rather than a character-level highlight — the line numbers tell you where to look.
Frequently asked questions
Why are near-identical lines shown as removed and added?
Because the comparison works line by line. A line with one word changed is a different line, so it appears as both. The line numbers point you at the pair, and reading them side by side is usually quicker than a character-level highlight would be.
Is there a size limit?
Three thousand lines a side. Comparing line by line costs time and memory in proportion to the two lengths multiplied together, so a much larger pair would lock the page rather than answer. For anything bigger, diff the files locally.
What do the two columns of numbers mean?
The left is the line number in the original, the right is the line number in the changed version. A removed line has only a left number and an added line only a right one, which is what makes it easy to find either line in its own file.
Does what I paste get sent anywhere?
No. Everything runs in your browser, on your own machine. Nothing is uploaded and nothing is logged. That matters more here than on most pages — source code, database queries and internal data are exactly the things that get pasted into tools like this, and most of them are a form that posts to a server.