Inline character-level diff between two strings.
Updated
Quick start
Paste original and changed text, see additions, deletions and unchanged runs highlighted inline.
Drop the baseline string into the left textarea.
Drop the modified version into the right textarea.
Insertions appear green, deletions red and struck-through. Counts at the top show characters added / removed / unchanged.
In-depth guide
Compare two strings character by character and see exactly which letters were added or removed. Built for short inputs — version numbers, sentences, JSON values — where line-level diff is too coarse.
1.4.2 vs 1.4.10.For comparing files or multi-line code, use the line-level text diff tool instead.
We use the classic longest-common-subsequence (LCS) algorithm with a 2D DP table. For each character we either match it (no change), delete it from A, or insert from B — backtracking through the table produces an optimal edit script.
Adjacent operations of the same type are coalesced into runs (so "hi" → "hello" shows as a single insertion of "ello" rather than four separate inserts).
No. The diff is computed in your browser using a longest-common-subsequence algorithm. Nothing leaves the page.
string-diff is character-level — useful for short strings, version numbers, single sentences, where you want to see exactly which letters changed. text-diff is line-level for comparing files or code.
Character-level diff is O(n × m) memory — we cap at 5,000 chars per side. Larger inputs fall back to line-level diff automatically. For huge files, use text-diff.
Yes — we split inputs by Unicode code point, so 🇺🇸 and é (e + combining accent) are treated as single graphemes where possible.
Inserts count characters present in B but absent in A; deletes count characters in A but not in B. Together with unchanged they equal the total characters in the diff.
Keeping it simple. Pre-normalise (lowercase, trim, collapse spaces) before pasting if you want to ignore those differences.
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