How FastConvert Works
Your files never leave your device. FastConvert runs entirely in your browser using WebAssembly and client-side JavaScript — no server uploads, no cloud processing, no data collection.
The Conversion Process
You Select Files
Choose files from your device using the upload button or drag and drop. Your files stay on your device — nothing is sent to a server at this point.
Browser Processes Locally
Our converter runs entirely inside your web browser using WebAssembly and JavaScript. The file is read, processed, and converted without ever leaving your device.
Conversion Happens Instantly
Using optimized WebAssembly libraries (like FFmpeg for video and Sharp-compatible codecs for images), the conversion is fast — often under a second for images and a few seconds for video.
You Download the Result
The converted file is generated in your browser memory and downloaded directly to your device. Once you navigate away, all data is automatically cleared.
Why Browser-Based Conversion Matters
Most online converters upload your files to their servers for processing. FastConvert is different.
Traditional Online Converters
- Files uploaded to remote servers
- Files may be stored or logged
- Speed limited by upload bandwidth
- Requires internet for processing
FastConvert (Browser-Based)
- Files processed 100% on your device
- Zero data stored or transmitted
- Near-instant conversion speed
- Works offline after page loads
The Technology Behind FastConvert
WebAssembly (Wasm)
We compile high-performance conversion libraries to WebAssembly, giving you near-native speed right in the browser. This is the same technology used by Figma, Google Earth, and AutoCAD on the web.
Canvas API
For image format conversions, we leverage the browser's built-in Canvas API to decode and re-encode images. This means the conversion uses your device's optimized graphics pipeline.
Web Workers
Heavy conversions run in background threads using Web Workers, so the page stays responsive while your files are being processed. You can even convert multiple files simultaneously.
File API & Blob Storage
Files are read using the browser's File API and stored temporarily as Blobs in memory. Nothing is written to disk or sent over the network. When you close the tab, the data is gone.
Ready to Convert?
Try it yourself — your files never leave your device.