Free Text Diff Checker

A text diff checker, also called a text compare tool, takes two blocks of text and shows you exactly what changed between them, so you do not have to read both versions and hunt for edits by eye. Paste the original on one side and the new version on the other. It is the quickest way to compare text and find differences online, and because it is a difference checker for text of any kind you can use it on a paragraph of prose, a config file or a few hundred lines of code.

Under the hood the comparison finds the longest common subsequence between the two texts, the longest run of lines that appear in the same order in both, and treats everything left over as an addition or a deletion. That is the same idea behind the Myers diff algorithm that Git and code review tools use, which is why the copyable output here reads like a standard unified diff. A line diff tells you a whole line changed, a word diff marks the exact words that differ and reads best for prose, and a character-level view is what catches a single transposed digit in something like an invoice number.

This runs entirely in your browser, so nothing is ever uploaded. That means you can safely compare private source code, a confidential contract or an API key, and it keeps working even with the network disconnected once the page has loaded. Common uses are reviewing edits before a pull request, comparing two drafts of a document, checking what changed in a config file and proofreading, and writers and legal teams lean on it to spot exactly which sentences were added, cut or reworded between two versions.