Text Diff Checker
Compare two blocks of text line by line. Same-device only — nothing is uploaded.
Advisory only. This tool highlights textual differences; it does not interpret them and is not legal advice — review important documents by hand.
How the comparison works
Each side is split into lines and aligned with a longest-common-subsequence pass, so unchanged lines stay put while additions and removals are marked at the edges. Format structured data first with the JSON formatter so whitespace differences do not hide real changes, and count the size of either side with the word counter. Comparing two statements instead? The checklists are a good place to see what each document is meant to contain.
Frequently asked questions
What does the diff really show?
It shows a line-level comparison: lines only on the left are marked removed, lines only on the right are marked added, and identical lines are shown unmarked.
Is my text uploaded?
No. The comparison runs entirely in your browser. Your text never leaves your device.
Is the result a legal or professional opinion?
No. It is an advisory text comparison only. Always review contract or document differences by hand — the tool does not interpret meaning.
How large a document can I compare?
There is a guard of roughly 200 KB of total input, so the browser stays responsive. Split larger files if needed.
Does it ignore trailing newlines?
Yes. A single trailing newline at the end of each side is ignored, so an otherwise identical file with one extra final newline does not show a false difference.
Can I compare two checklists or two versions of a form?
Yes — comparing two drafts is a common use. Format both sides first if they are JSON, using the JSON formatter, so the comparison is meaningful.
Related: normalise both sides first with the JSON formatter or the text case converter, and browse every browser-only tool on the all tools page.