Input A (Original)
Input B (Modified)
Comparison Result
AddedRemovedCode Diff Checker is a powerful tool for comparing two text or code snippets and visualizing the differences. Whether you're reviewing code changes, comparing configuration files, or validating JSON data, this tool highlights additions, deletions, and modifications in an easy-to-read format. Supports multiple comparison modes: character-by-character, word-by-word, line-by-line, JSON structure comparison, and unified diff patch format. Choose between side-by-side or unified view for maximum clarity.
How to Use
Paste or type your original text/code into 'Input A' and the modified version into 'Input B'. The tool automatically compares them in real-time as you type. Select a comparison mode: 'JSON' for structured JSON comparison with prettification, 'Lines' for line-by-line diff (default), 'Words' for word-level changes, 'Chars' for character-level precision, or 'Patch' to generate a unified diff patch. Toggle 'Side-by-Side View' to see inputs compared side-by-side with color-coded changes, or use unified view to see changes inline. Green highlights show additions, red shows deletions. Use 'Swap' to switch inputs, 'Reset' to clear, or 'Load Example' to see a demo.
Common Use Cases
Code Review
Compare original vs modified code during pull request reviews to spot exact changes.
Configuration Files
Verify changes between old and new config files (nginx.conf, package.json, .env files) before deployment.
JSON API Responses
Compare API responses before and after changes to validate data structure modifications.
Database Migrations
Compare SQL schema dumps to understand database changes.
Documentation Updates
Track changes in README or documentation files.
Debugging
Compare working vs broken code to identify what changed.
Version Control
Understand what changed between two Git commits or branches when you don't have access to Git.
Limitations & Important Notes
Very large files (>1MB) may cause performance issues in the browser—consider using command-line diff tools for massive files. Whitespace and line ending differences (LF vs CRLF) are detected and may show as changes even when content is identical—this is intentional for precise comparison. JSON mode requires valid JSON in both inputs; invalid JSON falls back to line-by-line comparison. Character-level diff ('Chars' mode) can be overwhelming for large texts—use 'Words' or 'Lines' mode for better readability. The tool compares text content only—binary files, images, or compiled code cannot be compared. For Git-integrated workflows, use git diff command which provides additional metadata (author, timestamp, commit hashes).