Diff Checker

This diff checker uses the Longest Common Subsequence algorithm, the same approach behind tools like Git diff. It builds a matrix comparing every line of both texts to find the longest sequence of matching lines. Lines present in the original but missing from the modified text are marked as removals. Lines in the modified text that do not appear in the original are marked as additions. This produces a clear, line-by-line view of exactly what changed between two versions of any document.

Developers use diff checkers to review code changes before committing, compare configuration files across environments, and verify that automated edits did not introduce unintended modifications. Writers and editors use them to track revisions between drafts. System administrators compare log files or server configurations to troubleshoot issues. Any time you need to answer the question "what changed between version A and version B," a diff checker gives you a fast, visual answer.

For the most useful diff output, make sure both texts use consistent line endings and indentation. If you are comparing code, auto-format both versions first so that style differences do not obscure meaningful changes. For large documents, consider comparing smaller sections at a time to keep the output manageable. You can also use the swap button to quickly reverse the original and modified sides if you pasted them in the wrong order. If you are comparing JSON payloads, try running them through our JSON Formatter first so structural differences are easier to spot. Our Hash Generator is also useful for quickly confirming whether two texts are identical by comparing their SHA-256 hashes.