Compare two texts
Compare two blocks of text and see exactly what changed.
A real diff
Comparing text properly means finding the longest common subsequence between the two versions — working out what genuinely moved, was added or was removed, rather than lining the two up and comparing position by position.
The difference is stark. Insert one line at the top of a document and a positional comparison reports every subsequent line as changed, which is useless. A proper diff reports one line added and everything else unchanged. The old version of this tool did it the first way; this one does not.
Reading the result
Lines are marked + for added and − for removed, with unchanged lines shown for context. The summary gives counts and the proportion unchanged, which is the quickest way to gauge how far two versions have drifted.
What it is good for
Comparing two drafts of a document, checking what a collaborator altered in a contract, verifying that a configuration file matches a known-good copy, or confirming whether two exports are identical.
Line-based, and what that implies
Comparison is by line. Change one word and the whole line shows as changed, which suits prose written one sentence or paragraph per line and suits code well. It is less helpful on a single enormous paragraph, where everything is one line — breaking long text at sentence boundaries first makes the output far more readable.
It runs in your browser
Both texts stay on your device. That matters here more than for most tools, since comparing two versions of a contract, a policy or unpublished work is exactly the case where uploading is unacceptable.
Comparing documents
For PDFs, extract both with PDF to Text first and paste the results here.
Common questions
Does it detect inserted lines properly?
Yes. It uses a longest-common-subsequence diff, so inserting a line reports one addition rather than marking everything changed.
Can it compare word by word?
Comparison is line-based. Splitting long paragraphs at sentence boundaries first makes the output much more readable.
Is my text uploaded?
No. Both versions stay in your browser.
Can I compare two PDFs?
Extract the text from each with PDF to Text, then paste both here.
Is there a size limit?
Only your device's memory. Very large files are slower because the comparison grows with the product of the line counts.