🔒 Privacy: everything runs in your browser. Nothing is uploaded.
About this text diff checker
A diff checker shows exactly what changed between two versions of a text. Writers use it to review edits from a client, developers compare config files or API responses, students check revisions, and anyone can spot the one changed clause in a long contract. Paste the original on the left and the new version on the right to see additions highlighted in green and deletions struck through in red.
Line mode is best for code, CSV files and configuration. Word mode is best for prose, where a single edited word would otherwise mark the whole paragraph as changed. The comparison uses a longest-common-subsequence algorithm, the same idea behind classic Unix diff, and runs entirely in your browser so confidential documents never leave your device.
For best results, normalise both texts before comparing: convert both to the same line endings, remove trailing spaces, and make sure smart quotes or non-breaking spaces copied from word processors are consistent, since those invisible differences show up as changes. When reviewing contracts or policies, use word mode and read every highlighted change in context, since a single added “not” can reverse the meaning of a clause. Developers comparing JSON should format both documents with the same indentation first, for example using our JSON formatter, so the diff shows real data changes instead of whitespace noise.
How to use it
- Paste the original text in the left box and the changed text in the right box.
- Choose Line or Word comparison.
- Review the highlighted additions (green) and removals (red).
FAQ
Is there a size limit?
Very large texts may be slow in the browser; the tool stops if the comparison would be too heavy.
Does it ignore whitespace?
No, whitespace differences are shown. Trim the texts first if they do not matter.
Can I compare files?
Open both files in an editor and paste their contents.
Is the text uploaded?
No, the diff is computed locally.