Are whitespace and newlines counted as differences?

Yes. Line-based diff means trailing spaces and CRLF vs LF show up. Trim the input first if you want them ignored.

Can I get a word- or character-level diff?

This tool uses line granularity. For finer diffs, compare a single line, or use json-diff for structured JSON values.

Thousands of lines work fine. Multi-megabyte input is not recommended since processing happens in the browser.

Example

Left:
first line
second line
third line

Right:
first line
second line modified
third line

  first line
- second line
+ second line modified
  third line

Default is line-based diff. Even small changes within a line show as `-` then `+`. Toggle between split (side-by-side) and unified (inline) views.

Usage / FAQ

Q.Are whitespace and newlines counted as differences?: A.Yes. Line-based diff means trailing spaces and CRLF vs LF show up. Trim the input first if you want them ignored.
Q.Can I get a word- or character-level diff?: A.This tool uses line granularity. For finer diffs, compare a single line, or use json-diff for structured JSON values.
Q.What about very large texts?: A.Thousands of lines work fine. Multi-megabyte input is not recommended since processing happens in the browser.

Fun facts

The 'minimum edit distance' problem was first solved in 1974 by Wagner–Fischer (O(mn) DP). Myers's 1986 O(ND) algorithm was the practical leap and became `git diff`'s default — its speed advantage shines when inputs are similar.
Wikipedia — Edit distance
Diff is fast on small changes (typical code review) because the LCS (Longest Common Subsequence) is long and the changes are small. Two wholly different documents can degrade to O(N²); git's `--patience` option exists precisely for that pathological case.
git — diff options
Diff units can be lines, words, or characters. Code diff is line-based; document diff (Google Docs, VS Code's inline diff) is word-based; precise analysis (DNA, NLP) is character-based — same algorithm, different token granularity.
Wikipedia — diff algorithm