Relay Mode (Office Tunnel)
Relay Mode lets you transfer files between devices on different networks — a remote worker and an office server, two separate offices, or any other cross-network scenario.
How it works
When Relay Mode is enabled, SwiftDrop routes the transfer through the Office Tunnel relay service:
- Both devices connect to the relay server on TCP port
47825. - The relay server creates a virtual tunnel between the two devices.
- Encrypted frames pass through the relay — the server sees ciphertext only, never the file contents.
- End-to-end encryption is maintained: session keys are negotiated directly between devices, not via the relay.
Enabling Relay Mode
- Open SwiftDrop → Settings → Connection.
- Toggle Enable Relay Mode on.
- Select your relay provider:
- Zashiron Managed Relay — available on Pro and above, no configuration needed.
- Self-hosted Office Space — Business/Enterprise, point to your own node IP.
Relay vs LAN comparison
| LAN | Relay | |
|---|---|---|
| Speed | Up to 900 MB/s | Limited by internet |
| Privacy | Fully local | End-to-end encrypted |
| Requires internet | No | Yes |
| Available on | All plans | Pro, Business, Enterprise |
Automatic fallback
If you have Relay Mode enabled and SwiftDrop detects that the two devices are on different subnets, it automatically falls back to relay. You do not need to toggle it manually per transfer.