Diff Checker
Compare two texts and find differences instantly. Additions and deletions highlighted.
What is a diff checker?
A diff checker is a tool that compares two blocks of text and highlights the differences between them. It shows added lines, removed lines, and unchanged lines so you can quickly see what changed between two versions of a document, code file, or any other text.
How to use the diff checker
- Paste the original text in the left box
- Paste the modified text in the right box
- Click "Compare" to see the differences
- Green highlights show additions, red with strikethrough shows deletions
- Use "Swap" to reverse the comparison direction
Common uses for diff checking
| Use Case | What You Compare |
|---|---|
| Code review | Two versions of a source file |
| Content editing | Original draft vs. revised draft |
| Configuration | Staging config vs. production config |
| Legal documents | Contract versions to spot changes |
| API responses | Expected vs. actual JSON output |
Frequently Asked Questions
Does this tool compare words or lines?
This tool compares text line by line, which is the standard diff algorithm used by Git and other version control systems. It is the most useful mode for code, configuration files, and structured text.
Is my data safe?
Yes. All comparison happens entirely in your browser. Your text is never sent to any server — it stays on your device.
Can I compare large files?
This tool handles texts up to several thousand lines. For very large files (10,000+ lines), consider using a desktop tool like VS Code's built-in diff or the command-line diff utility.