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Free Online Code Diff Checker with Syntax Highlighting

Compare code files side-by-side with syntax highlighting for 20+ languages. Fast, free, and private with support for JavaScript, Python, Java, and more. Need to compare plain text? Try our text diff checker.

Common Use Cases for Code Diff Checker

  • Code Review: Compare code changes during pull request reviews with syntax highlighting to identify modifications, bugs, or style issues.
  • Refactoring Validation: Verify that refactored code maintains the same logic by comparing before and after versions with language-aware highlighting.
  • Merge Conflict Resolution: Side-by-side comparison of conflicting code branches to understand differences and merge changes accurately.
  • Debugging: Compare working vs broken code versions to identify when bugs were introduced and what changed.
  • API Schema Changes: Diff JSON or XML API schemas to understand breaking changes between versions and update integration code.
  • Learning & Education: Compare example code with student submissions or different implementation approaches to teach best practices.

Professional Code Comparison Features

Syntax Highlighting for 20+ Languages

Powered by Monaco Editor (VS Code's editor), supporting JavaScript, TypeScript, Python, Java, C++, PHP, Go, Ruby, HTML, CSS, JSON, XML, YAML, and more with industry-standard syntax highlighting.

Side-by-Side & Inline Views

Choose between side-by-side comparison for full context or inline diff view for a unified perspective. Changes are color-coded with line-level and character-level highlighting.

100% Private & Secure

All code comparison happens entirely in your browser. Your source code is never uploaded to any server, ensuring complete privacy and security for proprietary or sensitive code.

How to Use the Code Diff Tool

Paste your original code in the left editor and the modified version in the right editor. Select your programming language for accurate syntax highlighting. Differences will be highlighted instantly with additions in green and deletions in red. Perfect for code reviews, debugging, refactoring validation, and merge conflict resolution. For comparing visual changes, check out our image diff checker.

Frequently Asked Questions