Text Diff Checker - Compare Two Text Blocks Online
Text Diff Checker
Line-by-Line Text Comparison
Understanding Text Diffing
Document Comparison
Compare two versions of a contract, article, or configuration file to see exactly what changed.
Code Review Prep
Quickly compare a code snippet before and after an edit without setting up a full version control diff.
Spotting Subtle Edits
Catch small, easy-to-miss wording or value changes buried in a large block of text.
Local Processing
Both text blocks stay in your browser — comparison runs entirely client-side.
How This Diff Algorithm Works
This tool compares text line by line using the Longest Common Subsequence (LCS) algorithm — the same underlying approach used by most version control diff tools. Lines that appear unchanged in both texts are matched first; everything else is marked as either removed (only in the original) or added (only in the modified version), giving you the smallest possible set of differences.
Key Takeaways
- Line-Level Comparison: Diffing works on whole lines, not individual characters.
- Color-Coded Output: Added lines are highlighted green, removed lines red.
- Client-Side Only: All comparison happens locally in your browser — no data is ever sent to a server.