As a hobby music producer, I often needed to share large WAVs, but existing services didn't really do it for me. Discord's 50MB limit was frustrating, and Google Drive, MEGA, Dropbox etc. felt cumbersome, so I started making transfer.zip. I rarely need to save my transfered files permanently, I just want to transfer them, and I think many others do too. Because the Quick Share feature never stores the files anywhere, there are no file size or bandwidth limitations!

Transfer.zip is easy to set up locally, to self-host or contribute to the codebase.

Quick Share uses WebRTC for peer-to-peer data transfer, meaning the files are streamed directly between peers and not stored anywhere in the process, not even on transfer.zip servers. To let peers initially discover each other, a signaling server is implemented in NodeJS using WebSockets, which importantly no sensitive data is sent through. In addition, the file data is end-to-end encrypted using AES-GCM with a client-side 256 bit generated key, meaning if someone could impersonate a peer or capture the traffic, they would not be able to decrypt the file without knowing the key. Because the file is streamed directly between peers, there are no file size or bandwidth limitations. The easiest way to Quick Share a file is to scan the QR code containing the file link and encryption key. It is also possible to copy the link and share it to the recipient over what medium you prefer the most.

Because of how peer-to-peer works, some network firewalls may not allow direct connections between devices. In that case, the peer-to-peer connection can fallback to using the signalling server as a relay, effectively bypassing network firewall limitations.

Transfer.zip also supports permanent file transfers, but currently not on the self-hosted version. That could be enabled in the future by making the API open source and self-hostable.

0-byte files gets stuck on transmit.

On Firefox mobile, sending files using Quick Share does not work at the moment. This could have something to do with the path being changed after the file has been chosen in the file picker, but not been read yet. This is under investigation.

Sending files from some Safari browsers is buggy at the moment, it has something to do with Safari terminating the WebSocket connection when unfocusing the window.

To setup self-hosting, copy the file web-server/example.env to web-server/.env. This will enable only the core features for Quick Share and the relay to function.

Then, to build and deploy transfer.zip, use docker compose.

docker compose build && docker compose up

This will listen for connections on localhost:9001, the signaling server will be proxied through the web-server on the /ws endpoint on the same port. When self-hosting, it is recommended to put transfer.zip behind a reverse-proxy with https. For Apache, the configuration needs to include these lines for the reverse proxy to function:

ProxyPreserveHost On

ProxyPass /ws ws://localhost:9001/ws
ProxyPassReverse /ws ws://localhost:9001/ws

ProxyPass / http://localhost:9001/
ProxyPassReverse / http://localhost:9001/

When developing, install all dependencies with cd web-server && npm i, then run the dev.sh script. It will start the signalling server and the web server for you.

./dev.sh