I Built a Privacy-First, Syntax-Aware Diff Tool because "Text Compare" Wasn't Enough

The Problem with "Generic" Diff Tools

We’ve all been there. You have a local version of a file and a version from production (or a snippet from StackOverflow), and something is breaking. You paste them into a generic "Online Diff Checker."

The result? A wall of black text with red and green backgrounds.

While this works for plain English, it is terrible for code. Without Syntax Highlighting, skimming through 500 lines of JSON, Rust, or Python to find a missing bracket or a variable type change is mentally draining.

Furthermore, most online tools require you to upload your data to their server to process the diff. If you are working on proprietary code, API keys, or client data, pasting that into a random web form is a security nightmare.

Enter Diff Guru 2.0: Now with Language Awareness

I built Diff Guru to solve the privacy issue by making it 100% client-side with unlimited merge capabilities. But today, I’m excited to announce a massive update: Language-Specific Syntax Highlighting.

We now support over 20+ languages and formats. We don't just compare text; we render it with the same syntax coloring you are used to in VS Code.

What’s New?

We’ve added dedicated support and highlighting for:

• 
  Modern Stack: TypeScript, JavaScript, React/JSX


• 
  Backend: Python, Go, Rust, Java, C#, PHP, Ruby


• 
  Systems: C, C++, Dockerfile


• 
  Mobile: Swift, Kotlin


• 
  Data/Config: JSON, XML, YAML, SQL, CSS, SCSS

Why Syntax Highlighting Matters in a Diff Tool

It reduces cognitive load.

If you are comparing two JSON ** files, seeing keys in one color and string values in another makes the structure pop immediately. If you are comparing **Rust, seeing lifetimes and macros highlighted helps you distinguish logic changes from syntax noise.

Try it out

You can try the specific tools here based on your stack:

🐍 Python Diff Checker

🦀 Rust Diff Checker

☕ Java Diff Checker

🐳 Dockerfile Diff

Roadmap

I am currently working on adding even more languages.

I built this tool to be free, fast, and private. I’d love to hear your feedback! If you find a language we are missing or a bug in the highlighting, let me know in the comments.

Happy Coding!