Text Diff Checker
Compare two blocks of text and see exactly what changed — updates automatically as you type. Runs entirely in your browser.
How it works
The comparison runs entirely in your browser using a standard text-diffing algorithm and updates automatically as you type. Word-by-word mode highlights individual word changes within otherwise similar text; line-by-line mode is better for comparing structured content like code or lists, and also offers a side-by-side view.
Worked examples
Compare The invoice is due on 15 March and totals 1,200 dollars with the same sentence ending 30 March and 1,250 dollars. In word-by-word mode, 15 is struck through in red and 30 is highlighted in green, and the amount shows 200 removed and 250 added, because the comma splits 1,200 into 1, and 200. The counter reads +2 added, -2 removed.
In line-by-line mode, comparing apples, bananas, cherries with apples, blueberries, cherries, dates (one per line) marks the whole bananas line as removed, blueberries as added, and dates as added at the end.
Reading the result
- Green is text that only exists in the changed version. Red with a line through it exists only in the original.
- The counter counts blocks of change, not words or lines. One highlighted phrase of five words counts once.
- Comparison is case-sensitive, so Hello and hello are a change.
- Word mode ignores changes that are only spacing. If you need to catch extra spaces or tabs, use line mode.
- In line mode a missing final newline also marks the last line as changed, even though it looks identical.
Tips for cleaner comparisons
Paste both versions from the same kind of source. Curly quotes against straight quotes, non-breaking spaces and different dash characters show up as differences even though they look alike. Use word mode for prose such as contracts and articles, and line mode for code, configuration files and lists. Very long documents are diffed in your browser, so a huge paste may take a moment.
Frequently asked questions
What's the difference between word-by-word and line-by-line comparison?
Word-by-word highlights individual changed words within otherwise similar sentences, which suits prose. Line-by-line treats each line as a unit and is better for code, lists, or other structured text.
Is my text uploaded anywhere?
No — the comparison runs entirely in your browser. Neither text is sent to a server.
Why does the counter say 1 added when I changed several words?
The counter counts contiguous blocks of change, not individual words. A phrase replaced in one place is one removed block and one added block, however many words it contains.
Does the comparison ignore capitalization or whitespace?
Capitalization is not ignored, so a changed letter case is shown as a difference. Word mode ignores whitespace-only differences, while line mode compares lines exactly.
What happens with very large texts?
The comparison stops after about two seconds and shows a message if the texts are too large or too different to compare. Compare smaller sections, or use line-by-line mode for long structured text.