This compares two blocks of text line by line and shows exactly what was added, removed, or left unchanged. It uses the same longest common subsequence approach behind most version control diff tools, which finds a genuinely minimal set of changes rather than flagging every line as different the moment something shifts around.
How to use it
- Paste the original version into the first box.
- Paste the changed version into the second box.
- Click compare.
- Read the result, with added lines in green and removed lines in red.
- Check the counts at the bottom for a quick summary of what changed.
When it helps
- Seeing exactly what changed between two drafts before sending an update.
- Comparing two versions of a config file to spot an unintended change.
- Checking what a colleague edited in a shared document.
- Verifying that a find and replace only changed what you meant it to.
- Comparing two versions of code pasted from different sources or branches.
Good to know
- Compare text with consistent formatting. Mixing tabs and spaces between the two versions can make unrelated lines look changed.
- For a long document, compare section by section rather than the whole thing at once.
- Remember this compares whole lines, so a one character change still highlights the entire line.
- For code specifically, a diff tool built into your editor or version control system usually gives more context, like syntax highlighting, than a plain text comparison like this one.
- When reviewing a long document's changes, skim the added and removed counts first to get a sense of scale before reading through every highlighted line.
Questions
Does this compare word by word or line by line?
Line by line. If a single word changes within a line, the whole line shows as one removed line and one added line, rather than highlighting just the word.
Why does moving a paragraph show as both an addition and a removal?
The algorithm finds the longest matching sequence of lines in order, so a paragraph moved to a new position looks like it was removed from its old spot and added at the new one.
Can I compare files instead of pasted text?
This works with pasted text. Open each file in a text editor, copy the contents, and paste them into the two boxes.
Can this compare more than two versions at once?
No, it compares exactly two blocks of text. For three or more versions, you'd run several comparisons in pairs.
Does trailing whitespace count as a difference?
Yes, since the comparison works on exact line content, a trailing space can flag a line as changed even if it looks identical.
Does capitalisation count as a difference?
Yes, since the comparison is exact, 'Hello' and 'hello' on otherwise identical lines will be flagged as a change.