Developer Tools
Code Diff
Compare two code snippets side-by-side with syntax highlighting, character-level change detection, and unified diff view. Supports 30+ languages. 100% private.
Free Online Code Diff — Compare Code Side-by-Side
What Is a Code Diff Tool?
A code diff tool compares two versions of code and highlights the differences between them — additions, deletions, and modifications. It is an essential tool for developers during code reviews, debugging, merge conflict resolution, and comparing configuration files across environments. Our free online code diff provides syntax-aware comparison with character-level precision, supporting 30+ programming languages with syntax highlighting — all running 100% client-side in your browser for complete privacy.
How to Use This Code Diff Tool
Paste your original code in the left editor and the modified version in the right editor. Click "Compare" or press Ctrl+Enter to generate the diff. The tool auto-detects the programming language and applies appropriate syntax highlighting. Additions appear in green, deletions in red, and modifications show both old and new versions with character-level highlighting of the exact changes. Switch between side-by-side and unified views using the toggle button. You can also drag and drop files directly into either pane.
Key Features
- Syntax-aware diffing — language detection with highlighting in 30+ languages, free of charge
- Character-level precision — highlights exact changed characters within each line, not just whole lines
- Dual view modes — side-by-side split view and unified inline view with one-click toggle
- Smart ignore options — toggle whitespace, case sensitivity, and comment ignoring
- File drag-and-drop — drop files directly into either editor pane
- Keyboard shortcuts — Ctrl+Enter to compare, Ctrl+Shift+U to toggle unified view
Why Choose Our Code Diff Tool?
Unlike Diffchecker.com, which locks syntax highlighting behind a $9/month Pro plan, our tool provides full syntax-aware diffing completely free. Everything runs client-side in your browser — your code never leaves your device, making it safe for proprietary source code, configuration files with secrets, and internal project code. There are no signup requirements, no daily limits, and no cloud storage upsells. The Monaco-powered editors provide the same experience as VS Code, with familiar keybindings and language support.
Common Use Cases
- Code reviews — comparing two versions of a function or file outside of GitHub or GitLab
- Configuration diff — comparing deployment configs across staging and production environments
- Debugging regressions — diffing two versions of code to find what changed
- Learning — comparing your solution with reference code or instructor feedback
- Documentation — diffing Markdown or AsciiDoc source files
Tips and Best Practices
Use the whitespace ignore option when comparing code that has been reformatted but not functionally changed — this eliminates noise from indentation and line ending differences. For large files, the collapse unchanged regions feature hides identical sections and lets you focus on the actual changes. When sharing diffs with teammates, use the unified view to copy a patch-style output that is easy to paste into Slack or email. If you are comparing API responses (JSON), paste them into both editors and the tool will highlight structural differences with proper JSON syntax highlighting.