100% Client-Side • Auto-saving LocalStorage

Text Diff Checker & Notepad

Jot down secure notes or find exact line-by-line differences between two text strings without server tracking.

Why use an offline Diff Checker?

Developers and writers frequently need to compare code files, legal documents, or configuration files. If you paste proprietary software code or sensitive internal memos into a cloud-based diff checker, those strings can be intercepted, cached, or logged by third parties.

This diff checker implements the Longest Common Subsequence (LCS) algorithm entirely in JavaScript within your browser.