How to Visualize Code Diffs Online with Syntax Highlighting
Code diffs help developers understand what changed between two versions of code. While command-line diff tools work, a visual diff with syntax highlighting makes changes much easier to spot and review. This guide shows you how to visualize code diffs online using fixie.tools — a free tool with syntax highlighting and side-by-side comparison.
Step 1: Open the Code Diff Visualizer
Go to fixie.tools/code-diff. No signup needed.
Step 2: Paste Your Code Versions
Paste the original code in the left panel and the modified code in the right panel. The tool supports all popular programming languages for syntax highlighting.
Step 3: Select the Language
Choose the programming language for proper syntax highlighting. The tool supports JavaScript, Python, TypeScript, Java, C++, Go, Rust, Ruby, PHP, and dozens more.
Step 4: Review the Diff
Added lines are highlighted in green, removed lines in red, and modified lines show the specific characters that changed. Use the side-by-side or unified view to review changes.
Step 5: Copy or Share Results
Copy the diff output or share a link. The visual diff is useful for code reviews, debugging, and documenting changes in pull requests or documentation.