How to Compare Text & Code Privately Online
LocalDiff.dev is a free, privacy-first text and code comparison tool that runs entirely in your browser. Unlike other online diff tools, your data never leaves your machine — there are no server uploads, no data logging, and no privacy risks.
Why Use LocalDiff.dev?
100% Private
All diff processing happens in your browser. No text is ever uploaded to any server. Perfect for sensitive code, contracts, or confidential data.
AI-Powered Merge
Use Google Gemini AI to intelligently resolve merge conflicts. The AI analyzes context and suggests the best merge strategy.
Word-Level Diffs
See exactly which words changed within each line, not just which lines are different. With syntax highlighting for popular languages.
Zero Setup
No downloads, no installation, no sign-up. Just open your browser and start comparing. Works on desktop and mobile.
Step-by-Step Guide
1. Input Your Content
You have three ways to input content into each panel:
- Paste: Copy-paste text directly into the "Original" (left) and "Modified" (right) text areas
- Upload: Click the upload button to select a local file
- URL Fetch: Enter a URL and click Fetch to load remote content
2. Compare
Click the Compare Sources button at the bottom of the screen. You'll see your differences highlighted in a visual diff view.
3. Choose Your View
- Split View: Side-by-side comparison with the original on the left and modified on the right
- Unified View: Traditional unified diff format showing all changes in a single column
4. Merge Changes
Hover over any changed block to see merge actions. You can:
- Keep the original version
- Accept the modified version
- Use AI-powered smart merge for complex conflicts
5. Export Results
Download the merged result as a text file, or copy it to your clipboard.
Supported File Types
LocalDiff.dev works with any text-based content including:
- Source code: JavaScript, TypeScript, Python, Go, Rust, Java, C/C++
- Configuration: JSON, YAML, XML, TOML, INI, .env
- Documentation: Markdown, plain text, HTML, CSS
- Data: CSV, SQL, shell scripts
Frequently Asked Questions
- Is my data safe?
- Yes. All diff comparisons happen locally in your browser. Your data is never uploaded to any server. The only exception is if you use the optional AI merge feature, which sends only the relevant text chunks to the Gemini API.
- Do I need to create an account?
- No. LocalDiff.dev works without any sign-up or login.
- Is there a file size limit?
- The free tier supports up to 100,000 characters per panel. Enterprise users have no limits.
- Can I compare binary files like images or PDFs?
- Currently, LocalDiff.dev supports text-based files only. Binary file comparison is on our roadmap.
- Does it work offline?
- Core diff features work without an internet connection. AI-powered features require connectivity.