Comparing two versions of a document by eye is slow and misses small edits.
Diff Checker aligns the two texts and marks every addition and removal, with ignore-case, ignore-whitespace and trim controls plus a line or word compare mode.
How to use Diff Checker
- Paste the original text on the left and the changed text on the right.
- Pick Line or Word comparison, then toggle Ignore case, Ignore whitespace or Trim line ends to skip trivial differences.
- Read the highlighted result; copy or download the marked diff.
Use cases
- Reviewing a contract revision against the signed original.
- Checking which clauses changed between two policy drafts.
- Verifying a config file was edited as intended.
Good to know
Diff Checker uses a longest-common-subsequence alignment, so it shows the smallest set of additions and removals rather than a naive line-by-line overlay. The ignore-case, ignore-whitespace and trim options only affect matching, never the text shown. Very large inputs wait for a Run comparison click so the page stays responsive.
Frequently asked questions
Can I compare by line or by word?
Yes. Use the compare-mode control to switch between line-by-line and word-by-word; line suits structural edits and word pinpoints small wording changes.
Do the ignore options change my text?
No. Ignore case, ignore whitespace and trim affect only how lines are matched; the output always shows your original characters.
What happens with a very large comparison?
Above a size threshold the result is withheld until you press Run comparison, which keeps the browser responsive on big inputs.