Diff Checker
Compare two texts side-by-side and highlight differences
upload_file Upload Files to Compare
Upload two text files to compare them
Drop original file or click
Drop modified file or click
keyboard Keyboard Shortcuts
history Version History
Save versions to compare multiple revisions
Save the current modified text as a version to compare later.
No versions saved yet
Save your first version to start tracking changes
About the Diff Checker
Compare two blocks of text side-by-side with our free online diff checker. Instantly spot additions, deletions, and modifications with color-coded highlighting. Perfect for comparing code versions, documents, configurations, or any text content.
What is a Diff Checker?
A diff (short for "difference") checker compares two pieces of text and highlights what's changed between them. It uses algorithms similar to those in version control systems like Git. Each line is analyzed and marked as added (green), removed (red), or unchanged. Word-level diffing can show exactly which words changed within modified lines.
Key Features
- Side-by-Side View — See original and modified text in parallel columns with aligned changes
- Inline View — View changes interleaved in a single column, showing removed and added lines together
- Unified Diff — Git-style unified diff format with +/- prefixes, perfect for patches
- Word-Level Diff — Highlight exact word changes within modified lines
- Ignore Options — Ignore whitespace or case differences when comparing
- Line Numbers — Optional line numbers for easy reference
- Change Navigation — Jump between changes with Previous/Next buttons or F7/F8
- File Upload — Drag and drop or upload text files directly
- Version History — Save multiple revisions and compare any two versions against each other
Version History Feature
Track changes across multiple revisions with our built-in version history:
- Save Versions — Save snapshots of your text with custom names (v1.0, Draft 1, etc.)
- Compare Any Two Versions — Select any two saved versions to compare their differences
- Quick Load — Load any version directly into the Original or Modified panel
- Export/Download — Export all versions as JSON or download individual versions
- Local Storage — Versions are saved in your browser and persist across sessions
View Modes Explained
| View Mode | Description | Best For |
|---|---|---|
| Side by Side | Two columns showing original and modified text aligned by line | Comparing code, seeing context around changes |
| Inline | Single column with removed/added lines shown sequentially | Reviewing changes in reading order |
| Unified | Git-style format with @@ markers and +/- prefixes | Creating patches, technical documentation |
Common Use Cases
- Code Review — Compare two versions of source code to see what changed
- Document Comparison — Compare drafts of documents, contracts, or articles
- Configuration Files — See differences between config files on different environments
- Debug Changes — Find exactly what changed when something stopped working
- Merge Conflicts — Understand conflicting changes when merging branches
- Text Deduplication — Verify if two texts are truly identical
Understanding the Colors
- Red background — Lines or words that were removed (in original but not modified)
- Green background — Lines or words that were added (in modified but not original)
- Yellow background — Lines that were modified (content changed)
- No highlight — Lines that are identical in both texts
Tips for Effective Comparison
- Use Ignore whitespace when comparing code with different formatting
- Enable Word-level diff to see exactly which words changed in modified lines
- Use the Unified view when you need to share or document changes
- Press F8 to quickly jump to the next change
Privacy & Security
All text comparison happens directly in your browser using JavaScript. Your texts are never sent to any server, making this tool completely safe for comparing proprietary code, sensitive documents, or confidential content.