Text Diff Checker
Paste an original text and a changed one to see every difference highlighted. Use it to review edits, compare drafts, check configuration files or spot what changed between two versions.
Your text stays in this browser tab. Nothing is uploaded, saved or logged.
How the Text Diff Checker works
By default the texts are compared line by line using Myers’ algorithm, the same method behind git diff. It finds the smallest set of added and removed lines that turns the first text into the second. A line that was edited appears as one removal and one addition, with the words that changed highlighted inside them. A block of text that was moved shows up as removed in one place and added in another.
Word mode and character mode compare the whole texts as running text instead of lines, which suits sentences and paragraphs. Changes are shown inline, with removed text struck through and added text underlined, so the difference never depends on colour alone. Characters are compared as visible characters, so an emoji or an accented letter counts as one.
“Ignore case” and “Ignore spaces” treat texts that differ only in capital letters or in spacing as equal. Line-ending styles (Windows, Mac and Linux) and a final line break are never counted as differences. Texts with more than 2,000 insertions and deletions between them are too different for a detailed comparison, so the part that differs is shown as one removed block and one added block, with a notice. Everything runs in your browser and neither text is uploaded.
How to use it
- Paste the original text on the left and the changed text on the right.
- Choose lines, words or characters, and whether to ignore case or spacing.
- Read the highlighted result, switch between unified and side-by-side views, or copy it as a unified diff.
Example
Two versions of a short checklist, compared line by line.
Original
Project plan - Write the draft - Review with the team - Publish on Friday
Changed
Project plan - Write the first draft - Review with the team - Publish on Monday - Send the newsletter
Unified diff — 3 added, 2 removed, 2 unchanged
--- original +++ changed @@ -1,4 +1,5 @@ Project plan -- Write the draft +- Write the first draft - Review with the team -- Publish on Friday +- Publish on Monday +- Send the newsletter
Frequently asked questions
How is this different from comparing in a word processor?
It works on plain text and shows a precise, line-numbered result that you can copy as a standard unified diff. A word processor compares formatted documents and tracks changes instead, which is a different job.
Why is a moved paragraph shown as removed and added?
A diff describes the smallest set of line changes between two texts, and it has no notion of moving. A moved block is therefore reported as a removal at its old place and an addition at its new one.
Can I compare code or configuration files?
Yes. Paste the contents of the two files. Line mode with “Ignore spaces” turned on is useful when only the indentation changed, and the unified diff output follows the format that git and patch understand.
What does “too different for a detailed comparison” mean?
To stay fast and responsive, the detailed comparison stops when two texts need more than 2,000 insertions and deletions. The differing section is then shown as a single replaced block. Compare smaller parts of the text if you need line-by-line detail.