Code Diff & Comparison Tool

What is a Code Diff Tool?

A code diff (difference) tool is an essential utility that compares two versions of code or text and highlights the differences between them. It shows exactly what lines have been added, removed, or modified, making it invaluable for code reviews, debugging, understanding changes between versions, and resolving merge conflicts. This tool provides both side-by-side and unified diff views with syntax highlighting for better readability.

How to Use This Tool

1. Paste your original code in the left panel and modified code in the right panel
2. Select the programming language for syntax highlighting (JavaScript, Python, HTML, etc.)
3. Choose between Side-by-Side or Unified view mode based on your preference
4. Toggle "Ignore Whitespace" to focus on meaningful changes and ignore formatting differences
5. Click "Compare" to see the differences with color-coded highlighting
6. Green highlights show additions, red shows deletions, and gray shows unchanged lines
7. Use "Swap" to reverse the original and modified code (useful for seeing reverse diff)
8. Click "Copy Diff" to copy the comparison result to your clipboard
9. View statistics showing the number of additions, deletions, and unchanged lines

Common Use Cases

• Code Review: Compare code changes in pull requests to understand what was modified
• Debugging: Identify what changed between a working version and a broken version of your code
• Version Comparison: See differences between two versions of a file or function
• Merge Conflict Resolution: Understand conflicting changes when merging branches
• Refactoring Analysis: Compare original code with refactored code to verify improvements
• Configuration Changes: Compare configuration files to see what settings were modified
• Learning & Teaching: Show students or colleagues how code evolved or was improved
• Documentation: Create visual examples of code changes for technical documentation
• API Changes: Compare old and new API implementations to understand breaking changes

Features

• Side-by-Side View: Compare code in two columns with aligned changes for easy visual comparison
• Unified View: See all changes in a single column with +/- prefixes like Git diffs
• Syntax Highlighting: Color-coded syntax for 10+ programming languages including JavaScript, Python, JSON, HTML, and CSS
• Line-by-Line Detection: Precise identification of added, removed, and unchanged lines
• Ignore Whitespace: Option to ignore spacing and indentation changes to focus on code logic
• Change Statistics: See counts of additions, deletions, and total changes at a glance
• Copy Functionality: One-click copy of the diff output for sharing or documentation
• Swap Feature: Quickly reverse original and modified to see the diff from the other direction
• Client-side Processing: All comparisons happen in your browser - your code stays private
• Responsive Design: Works on desktop and mobile devices

View Modes Explained

Side-by-Side View

The side-by-side view displays the original code on the left and modified code on the right in two columns. This makes it easy to see exactly what changed at each position. Lines that were removed appear in red on the left with empty space on the right, while lines that were added appear in green on the right with empty space on the left. Unchanged lines appear in gray on both sides. This view is ideal for reviewing changes in a visual, aligned manner.

Unified View

The unified view shows all changes in a single column, similar to Git diff output. Lines that were removed are prefixed with a minus sign (-) and shown in red, while lines that were added are prefixed with a plus sign (+) and shown in green. Unchanged lines have no prefix and appear in gray. This view is more compact and is familiar to developers who work with version control systems like Git.

Frequently Asked Questions

Is this code diff tool free?

Yes! This code diff and comparison tool is completely free to use with no registration, no limits, and no hidden costs. Compare as many code files as you need.

Is my code secure and private?

Absolutely. All code comparison happens entirely in your browser using JavaScript. Your code never leaves your computer and is never sent to any server. This makes it completely safe to use with proprietary code, sensitive business logic, or private projects.

What diff algorithm is used?

This tool uses the industry-standard Myers diff algorithm (via the diff library) which is the same algorithm used by Git and other version control systems. It performs line-by-line comparison to detect changes accurately and efficiently.

Can I compare large files?

Yes! Since all processing happens in your browser, there's no server-side file size limit. You can compare files with thousands of lines, though very large files may take a moment to process depending on your computer's performance.

Does this work offline?

Yes! Once the page is loaded, all comparison functionality works offline. The tool doesn't require an internet connection to compare code.

What programming languages are supported?

The tool supports syntax highlighting for JavaScript, TypeScript, Python, JSON, HTML, CSS, PHP, Ruby, Go, Java, and more. The comparison works with any text-based code regardless of language, but syntax highlighting enhances readability for supported languages.

What does "Ignore Whitespace" do?

When enabled, the "Ignore Whitespace" option tells the diff algorithm to ignore changes that only affect spaces, tabs, or indentation. This is useful when you want to focus on actual code logic changes rather than formatting differences. For example, if you reformatted code with a different indentation style, enabling this option will hide those changes and show only the meaningful code modifications.

Can I export the diff results?

Yes! You can use the "Copy Diff" button to copy the comparison results to your clipboard. This allows you to paste the diff into documentation, code reviews, emails, or any other application.

How is this different from Git diff?

This tool provides a visual, web-based interface for comparing any two code snippets without needing Git or version control. While Git diff works with repository history, this tool lets you paste any two pieces of code and instantly see the differences with syntax highlighting. It's perfect for ad-hoc comparisons, learning, or when you don't have access to your development environment.

Are there keyboard shortcuts available?

Yes! Use Tab to navigate between buttons and text areas, Enter to activate focused buttons, and Escape while focused on text areas to quickly clear content.