Diff Checker

It uses a Longest Common Subsequence (LCS) based diff algorithm. LCS finds the longest sequence of lines common to both texts, then marks remaining lines as additions or deletions — the same core approach used by Git and Unix diff.

Yes. The tool runs entirely in your browser, so there are no upload limits. However, very large files (tens of thousands of lines) may take a moment to compute because the LCS algorithm has O(n×m) time complexity.

No. All processing happens locally in your browser. Your text never leaves your machine, making it safe for comparing sensitive code, configs, or credentials.

This tool performs a line-by-line comparison. If a line exists in the original but not in the modified text, it is marked as a deletion (red). If it exists in the modified but not the original, it is an addition (green). Lines present in both are unchanged.

Not directly. A moved line appears as a deletion at its old position and an addition at its new position. This is consistent with how standard line-based diff tools work.