How to compare two texts
- Paste the original text on the left and the changed text on the right.
- Press Compare. Removed lines are marked with − and added lines with +, and within a changed line the exact words that differ are highlighted.
- Switch between Unified (one column, like git) and Side by side views. On a phone, the table scrolls sideways.
- Tick Ignore whitespace or Ignore case to hide differences that do not matter, and Changes only to hide unchanged lines.
- Download the result as a
.difffile to share or keep.
How the diff works
The checker uses the Myers diff algorithm, the same approach used by git and GNU diff. It finds the smallest set of line insertions and deletions that turns the first text into the second, so moved blocks and small edits are shown as clearly as possible. Changed lines are then compared word by word to pinpoint the edit.
Changes are marked with + and − symbols as well as colour, so the result is readable in any theme, when printed, and for people with colour vision deficiency.
It works for any plain text: code, configuration files, contracts, essays, translations, CSV exports or two versions of a list.
Privacy
Both texts are compared locally in your browser. Nothing is uploaded, so you can safely compare confidential documents and source code.
Can I compare Word or PDF files?
Copy the text out of the documents and paste it in. The checker compares plain text, so formatting such as bold or fonts is not compared.
Why is a whole line shown as changed for one character?
Diffs work line by line first. The changed word or character inside the line is then highlighted more strongly so you can spot it.
How large can the texts be?
Up to 20,000 lines on each side. Texts with many differences take longer, but typical files compare in well under a second.