Cross-network files and live text, end-to-end encrypted
Two online devices on different networks pair with a 6-digit code (or its link/QR) to send files or ephemeral text. Browser sessions use Relayium's TURN relay by design, but it only ever sees ciphertext; text message bodies are never stored by Relayium.
A transfer in four steps
- One person signs in and mints a 6-digit pairing code for a file or text session (or shares its join link / QR).
- The other person opens the link or enters the code — joining with a code needs no account.
- Optional (turn on advanced verification): both sides compare the same 6-digit verification code (SAS) out of band — a different value from the pairing code. A match confirms the X25519 endpoint public keys were not substituted, so the signaling service or TURN relay did not impersonate either endpoint or terminate the app-layer E2EE. TURN can still remain in the network path, carrying only ciphertext.
- With both devices online, the peer card's one action opens a shared workspace: one end-to-end encrypted connection, with the composer on screen by default and the file and folder controls under it. Files and live text messages travel together through TURN, which carries only ciphertext, for a bounded lifetime the workspace warns about before it ends. Relayium never stores message bodies; one message can contain up to 65,536 UTF-8 bytes.
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.
- Optional SAS anti-MITM check — Compare the 6-digit SAS out of band to confirm the X25519 endpoint public keys were not substituted. A match detects a signaling service or TURN relay impersonating an endpoint; it does not prove TURN is absent from the network path, where it carries only ciphertext.
- Relay sees only ciphertext — Cross-network browser transfers use a fast TURN relay by design for reliable connections across NAT — and it only ever carries ciphertext, never your keys or plaintext.
- Live, ephemeral text — Both devices must stay online. Relayium stores no message bodies or server-side history; a receiving endpoint can still copy or retain text. Each message supports up to 65,536 UTF-8 bytes.
- Cross-platform — Windows, macOS, Linux, Android, iOS — any modern browser, nothing to install.
- Free — Free to use within a monthly relay allowance; the person creating a file or text code signs in, while anyone joining with that code needs no account.
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, app-layer E2E and an out-of-band SAS check for X25519 endpoint-key substitution. A compromised relay or signaling server cannot silently impersonate an endpoint or terminate that encryption; TURN still carries ciphertext in the network path.
Frequently asked questions
Do my files or messages go through a server?
Cross-network browser sessions use Relayium's TURN relay by design, but files and messages are end-to-end encrypted, so it sees only ciphertext. Relayium does not store text message bodies.
Is a code required?
Yes: a 6-digit code (or its join link/QR), valid 5 minutes, pairs the two devices across networks. The server mints it uniformly at random from 0-9, so every digit is possible and a leading zero is ordinary — which also means you cannot invent one: only a code the server handed out will pair. It is not the same six digits as the verification code (SAS), which is derived from the two endpoint keys.
Do I need an account?
The person creating a pairing code for files or text signs in; anyone joining with that code needs no account.
Is it end-to-end encrypted?
Yes — X25519 + per-chunk AES-256-GCM. Comparing the SAS out of band confirms the endpoint public keys were not substituted, so the signaling service or TURN relay did not impersonate either endpoint or terminate the app-layer E2EE. TURN can still be in the network path, carrying only ciphertext.
Can I send text as well as files?
Yes. While both devices are online, send live ephemeral text up to 65,536 UTF-8 bytes per message. Relayium stores no message bodies or server-side history, although either endpoint can copy or retain received text.
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