Text Diff Checker
Compare two texts and see exactly what was added, removed and changed.
About this tool
Paste two versions separated by a line containing only `---` and see what changed between them.
It computes a real diff, matching lines by longest common subsequence rather than comparing line 1 to line 1. That distinction is the whole value: insert a single line at the top of a document and a positional comparison reports every line after it as changed, burying the one edit you were looking for.
Common questions
How do I separate the two versions?
A line containing only three dashes: ---. Everything above it is the old version, everything below is the new one.
Why not just compare line by line?
Because inserting one line at the top shifts everything, and a positional comparison then reports the whole document as changed. A proper diff finds the longest run of lines the two versions share and reports only the real edits.
Can it ignore whitespace?
Yes, with the option. Useful when comparing code that has been reindented, or text that has been reflowed — otherwise every line differs and none of the differences matter.
Is my text sent anywhere?
It is compared on this server and sent nowhere else. It is not stored unless you are signed in, in which case the run is saved to your history.