Last updated: 2026-07-09
Sending a file to another computer usually means uploading it somewhere first — a cloud drive, an email attachment, a chat app — and hoping the recipient can get it back out again. Relayium skips that step: it connects your browser directly to theirs, wherever in the world they are, and streams the file straight across.
This guide covers both cases — two computers on the same network, and two computers on completely different networks (different homes, offices, countries) — and shows exactly what each side needs to do.
Relayium runs entirely in the browser at relayium.com. There is nothing to install on either computer, and no third-party storage sits between you and the recipient: when a direct connection is possible, the file goes from one browser to the other and is never written to a server.
That matters for two reasons: speed (you are not bottlenecked by someone else's upload/download quota) and privacy (no copy of your file sits on a company's servers waiting to be requested, breached, or forgotten about).
If both computers are on the same Wi-Fi or LAN, Relayium finds them automatically — open relayium.com on both, and no account is needed on either side.
If the two computers are on different networks — your desktop at home and a colleague's laptop across the country, for instance — automatic discovery cannot reach across the internet, so Relayium uses a short pairing code instead. The person sending signs in to mint that code; the person receiving never needs an account, whether they type the code in or just open the link it generates.
Here is the full flow for two computers on different networks:
Most home and office networks let two browsers connect directly once they know about each other. Some corporate firewalls or strict NATs block that, though — in which case Relayium falls back to a TURN relay to carry the encrypted stream instead of failing outright.
The relay only ever sees ciphertext: the file is encrypted end-to-end (X25519 key exchange plus AES-256-GCM) before it ever leaves the sending browser, so the relay cannot read it any more than a random computer on the internet could. If the connection drops partway through, the transfer resumes instead of starting over.
You can send up to 1,000 files in one batch, folder structure included. There is no server-side size cap — the practical ceiling is set by the receiving browser.
Chrome and Edge stream incoming data straight to disk, so multi-gigabyte files are fine. Firefox and Safari buffer the file in memory instead, so on those keep a single file to roughly 200 MB or less. Each file is also checked end-to-end with a SHA-256 hash, so you know what arrives is byte-for-byte what was sent.
When a direct connection is possible, the file streams straight from one browser to the other and is never stored on a server. Only when a direct path can't be established (a strict firewall or NAT on one side) does it fall back to a relay — and even then the relay only ever sees encrypted ciphertext, never the file itself.
No. On the same network, neither side needs an account. Across different networks, the person sending signs in to create the pairing code — that's what lets Relayium mint and manage the code — but the person receiving never needs an account, whether they type in the code or just open the link.
Yes. The pairing code exists specifically for this case: two computers that aren't on the same local network connect directly, peer-to-peer, wherever each one is in the world, falling back to an encrypted relay only when a direct path isn't possible.
You can send up to 1,000 files in a single batch. There's no size cap enforced by the server — the limit is what the receiving browser can handle: essentially unlimited in Chrome or Edge (streamed to disk), and around 200 MB per file in Firefox or Safari (buffered in memory).
Open Relayium on both computers and send your first file across the internet — no cloud upload, no install, and the recipient never needs an account.
Try Relayium now