Text Diff Tool

No. The diff algorithm runs entirely in JavaScript in your browser. Your text never leaves your device — there are no API calls, no uploads, and no logging.

When two adjacent lines are changed (one removed, one added), the tool highlights only the characters that actually differ — not the whole line. This makes it easy to spot a single word or character change inside a long line.

Three modes are available. "Normal" treats all whitespace as significant. "Ignore leading/trailing" trims each line before comparing, so indentation differences are invisible. "Ignore all whitespace" removes every space and tab before comparing — useful for comparing minified vs. formatted code.

It copies the diff in standard unified diff (git patch) format — the same format produced by git diff. The patch starts with --- and +++ headers, followed by @@ hunk markers and ±-prefixed lines. You can save it as a .patch file and apply it with git apply or patch.

The tool uses the classic LCS (Longest Common Subsequence) algorithm on line arrays, implemented with a flat typed array (Int32Array) for efficiency. This is the same fundamental approach used by diff, git diff, and most diff tools.

Each side is capped at 2,000 lines before processing to keep the browser responsive. For most documents, config files, and code files this is more than enough. Very large texts (thousands of lines) should be compared with a dedicated command-line diff tool.