Text Diff Checker
Compare two texts and see added, removed, and unchanged lines side by side. Perfect for code, documents, and configs.
Original
Modified
Paste text into both fields above to see the diff
How to Use
Paste original text
Enter the original (before) text in the left field.
Paste modified text
Enter the modified (after) text in the right field.
View the diff
The diff updates automatically. Green lines are additions, red lines are deletions, and white lines are unchanged.
Filter results
Click "Show changes only" to hide unchanged lines and focus on what actually changed.
FAQ
This tool uses a Longest Common Subsequence (LCS) algorithm to compare lines of text and produce a minimal diff. It identifies which lines were added, removed, or kept the same.
The diff engine processes up to 2,000 lines per side. For larger inputs, only the first 2,000 lines of each field are compared.
Yes. The comparison is line-based and works with any plain text, including source code, configuration files, JSON, CSV, and more.
The left number is the line number in the original text; the right number is the line number in the modified text. Blank means the line does not exist in that version.
No. All comparison happens in your browser. Your text never leaves your device.