Compare two texts and see exactly what changed.
The Text Diff Checker compares two pieces of text side by side and highlights exactly what changed — additions in green, deletions in red. Use it to compare document versions, check edits, or spot changes between any two texts.
Paste the original ("old") version into the left box and the updated ("new") version into the right. Click Compare Texts. The diff panel below highlights additions in green and deletions in red, with unchanged words shown in a muted colour. The stats counter shows how many words were added and removed in total. Word-level diffing means single-character typos still render the whole word as a change — easy to spot. Useful for proofreading edits, contract revisions, before/after copywriting, and Git-free quick comparisons.
The tool splits both texts into tokens (words plus whitespace), then runs the classic Longest Common Subsequence algorithm. LCS finds the longest sequence of identical tokens that appear in both inputs in the same order — that's the unchanged backbone. Anything not in the LCS is either an addition (in the new only) or a deletion (in the old only). It's the same algorithm Git uses for source-code diffs, just applied to natural-language tokens. Complexity is O(n×m), so very long documents may take a moment to render.
Reviewing edits returned by a copy-editor, comparing two contract drafts, spotting changes between two versions of a configuration file, checking what an LLM rewrote, or auditing translation tweaks across a localisation pass.