Text Diff Checker
Compare two blocks of text line by line. Added and removed lines are highlighted with line numbers and change stats. Everything runs in your browser — nothing is uploaded.
About this tool
Compares the two texts line by line using a longest-common-subsequence algorithm — the same approach git diff is built on — so unchanged lines are matched up properly instead of everything after the first change being flagged. For very large inputs (over 2,000 lines per side) it falls back to a faster prefix/suffix comparison and tells you when it does. The ignore-whitespace toggle trims leading and trailing spaces before comparing, which is handy for re-indented code.
Your text never leaves the page — there is no server, no upload, and no tracking of tool inputs. You can safely diff config files, contracts, or anything else private.