Compare Files Online — Free File Diff Tool
Upload or drag and drop two text-based files to instantly compare them. See every added, removed, and changed line — no upload to any server.
Open the Tool — Free & InstantYour data never leaves your browser
No server processing
All diffing runs locally in your browser using JavaScript. Zero data transmitted.
No logging or storage
We do not store, log, or read your content. Nothing is saved anywhere.
Safe for sensitive content
Confidential code, config files, API keys — safe to compare here.
PII detection on share
Before any share link is generated, your content is scanned for emails, API keys, and tokens — with options to redact or encrypt.
Features
- ✓Drag and drop files directly onto the panels
- ✓Supports .txt, .json, .csv, .md, .js, .ts, .py, .yaml and more
- ✓Files are read locally — never uploaded
- ✓Side-by-side and unified diff views
- ✓Syntax highlighting for code files
- ✓Download diff as .patch or HTML
- ✓Share diff via URL (content stays in the link)
- ✓Works on any device, no install needed
Frequently Asked Questions
How do I compare two files online?
Drag and drop the original file onto the left panel and the modified file onto the right panel. The diff is computed instantly. You can also click the File button above each panel to browse and select files.
What file types are supported?
Any plain text file: .txt, .json, .csv, .xml, .yaml, .md, .js, .ts, .py, .go, .rs, .sql, .html, .css, and more. Binary files (images, PDFs, Office documents) are not supported.
Are my files uploaded to a server?
No. Files are read directly in your browser using the FileReader API. They never leave your device. This makes it safe for comparing confidential documents, config files, or source code.
Can I compare large files?
Yes, within reason. The tool handles files up to a few megabytes comfortably. Very large files may slow down the browser since all processing runs client-side.
Can I share the result with someone?
Yes — click Share to generate a URL with the diff content encoded in it. For very large files the URL may be long, but it works without any server.