I built browser-to-browser remote file access with WebRTC – no app required

I’ve been building a browser-first project called RelicBeam, and one feature I wanted was simple in theory: Open a folder on one device and temporarily browse it from another device without installing anything. That became Remote Files, part of RelicBeam’s Device Portal. The host selects a folder, another device joins with a QR/code, the host approves the connection, and the second device can browse, preview and download files. The folder itself is never uploaded to RelicBeam. File data travels over a WebRTC DataChannel. If a direct connection isn’t possible, my own TURN server relays the encrypted traffic. Device Portal traffic is end-to-end encrypted between the connected browsers. The interesting problems The file browser itself was actually the easy part. Android file pickers kept killing sessions When I added optional uploads, I noticed something odd during testing. The first upload worked, but after opening the Android file picker a few times, the Remote Files session could suddenly disconnect. It turned out Android can background or suspend the browser while the native file picker is open. That could temporarily drop the Socket.IO signaling connection, and my server was treating any disconnect as the viewer leaving permanently. The fix was a short reconnect grace period. Temporary disconnects now get time to recover, while explicit Leave and End session actions still terminate access immediately. Firefox and Safari can browse, but not host uploads Remote Files works read-only across browsers, but writable folder access is more limited. Chrome and Edge expose writable directory handles through the File System Access API, so a host can optionally allow remote uploads into the selected folder. Firefox and Safari don’t currently expose the same writable directory picker. So today: Chrome / Edge host Browse ✅ Preview ✅ Download ✅ Optional uploads ✅ Firefox / Safari host Browse ✅ Preview ✅ Download ✅ Host uploads ❌ Firefox and Safari can still be the remote device