Cross-network file transfer, end-to-end encrypted
Two devices on different networks pair with a 6-character code (or its link/QR). Files stream over an encrypted channel through a fast relay that only ever sees ciphertext — your keys never leave the two devices.
A transfer in four steps
- The sender signs in and mints a 6-character pairing code (or shares its join link / QR).
- The receiver opens the link or enters the code — no account needed to receive.
- Both sides verify the same 6-digit SAS on screen to rule out a man-in-the-middle.
- Files stream end-to-end encrypted (AES-256-GCM per chunk) through Relayium's fast relay, which carries only ciphertext it can't read.
Why transfer this way
- End-to-end encrypted — X25519 key exchange + per-chunk AES-256-GCM; keys are negotiated only between the two devices, so neither the relay nor the server can decrypt.
- SAS anti-MITM — Both screens show the same 6-digit code; matching it defeats even a compromised relay or signaling server.
- Relay sees only ciphertext — Cross-network transfers travel through a fast relay for a reliable connection across any NAT — and it only ever carries ciphertext, never your keys or plaintext.
- Cross-platform — Windows, macOS, Linux, Android, iOS — any modern browser, nothing to install.
- Free — Free to use within a monthly relay allowance; minting a code needs the sender signed in, the receiver joins anonymously.
Compared with the alternatives
vs AirDrop
AirDrop is Apple-only and same-vicinity; Relayium connects Windows, Android, iPhone and Mac across different networks, end-to-end encrypted, with just a browser.
vs Snapdrop / PairDrop
Those are same-network only; Relayium adds cross-network pairing plus app-layer E2E + a SAS code, so even a compromised relay or signaling server can't eavesdrop.
Frequently asked questions
Do my files go through a server?
The encrypted stream travels through Relayium's relay for a reliable cross-network connection — but it's end-to-end encrypted, so the relay only ever sees ciphertext it can't read.
Is a code required?
Yes: a 6-character code (or its join link/QR), valid 5 minutes, pairs the two devices across networks. The server mints it from the alphabet ACDEFHJKMNPRTWXY23456789 — no 0 and no 1, so nothing is mistaken for O or I — which also means you cannot invent one: only a code the server handed out will pair.
Do I need an account?
The sender signs in to mint a code; the receiver joins anonymously.
Is it end-to-end encrypted?
Yes — X25519 + per-chunk AES-256-GCM, verified with the SAS code, so neither the relay nor the server can decrypt.
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