How to compare text
- Paste the original on the left and the new version on the right.
- Choose how to compare: by line, word or character.
- Green shows text that was added; red with a strike shows text that was removed.
Common uses
- Writing and editing: see what an editor or co-author changed between drafts.
- Contracts and policies: catch quiet changes to terms, numbers and dates.
- Code: compare two versions of a function or config file before deploying.
- Data: spot differences between two lists, such as email or product exports.
How diffing works
The tool uses the Myers diff algorithm (the same idea behind git diff) to find the smallest set of insertions and deletions that turns one text into the other. Everything else is shown as unchanged.
Need to count the changes in words? Paste the result into the word counter. Fix capitalization differences with the case converter.
Last reviewed October 2026.
Frequently asked questions
What is a diff checker?
A diff checker compares two pieces of text and highlights what changed: lines or words that were added, removed or kept. It is handy for comparing document drafts, contracts, code and configuration files.
Is my text uploaded anywhere?
No. The comparison runs entirely in your browser, so confidential documents and code never leave your device.
What is the difference between line, word and character mode?
Line mode compares whole lines, which suits code and lists. Word mode highlights changed words within sentences, best for prose and contracts. Character mode shows the exact letters that changed, useful for spotting typos in short text.
Can it ignore case or extra spaces?
Yes. Tick "Ignore case" to treat A and a as the same, and "Ignore whitespace" to ignore differences in spaces and indentation.
How large can the texts be?
Comparisons of tens of thousands of lines work fine on most computers. Very large files in character mode may be slow, so use line mode for those.