+ added- removed unchanged
When you have two versions of the same document and no version history, spotting what changed by eye is slow and unreliable. This tool compares the two texts line by line using a longest common subsequence diff, the same approach used by version control systems. Lines that exist only in the second text are marked as added, lines that exist only in the first are marked as removed, and everything that matched is shown plain.
Colour is not the only signal. Every line is also prefixed with a plus, a minus or two spaces, so the diff stays readable if you copy it into a plain text email, a ticket or a chat message. Two options control how strict the matching is: ignoring case treats capitalisation changes as identical, and ignoring leading and trailing whitespace stops indentation edits from showing as rewrites.
How to use the Text Compare
- Paste the original version into the left box and the changed version into the right box.
- Choose whether to ignore case and whether to ignore leading and trailing whitespace.
- Click Compare Texts to see the line by line diff and the summary counts.
- Tick Hide unchanged lines to focus on the edits, or click Copy Diff to share the result.
Frequently asked questions
How does the comparison work?
It splits both texts into lines and finds the longest common subsequence between them, which is the longest run of lines appearing in both in the same order. Anything outside that run is reported as added or removed, so a moved block shows as one removal and one addition.
Does it highlight changes inside a line?
No, the comparison is line based. If a single word changes, the whole line appears once as removed and once as added. That keeps the output predictable and readable, and it matches how patch files and code review diffs present changes.
What do the ignore options actually change?
They affect matching only, not display. Ignore case makes Hello and hello count as the same line. Ignore leading and trailing whitespace strips spaces and tabs at both ends before comparing, so reindented lines are not reported as edits.
Is there a limit on how much text I can compare?
Each side accepts up to 2000 lines. That cap keeps the comparison fast in the browser, since the work grows with the product of both line counts. For longer documents, compare one chapter or section at a time.