Relayium

Relayium vs WeTransfer: encrypted links and live handoffs

Last updated: 2026-07-31

WeTransfer made sending big files feel effortless: drop a file, get a link, and the recipient downloads whenever they are ready — even if they were offline when you sent it. That asynchronous, no-account-to-receive experience is genuinely good, and it is why so many people reach for it.

This article compares the two fairly. For large files or later pickup, Relayium also recommends a stored link: unlike WeTransfer, its server keeps only zero-knowledge ciphertext. Relayium's realtime mode is a separate strength for quick small files and text while both sides stay online — direct on the same LAN and carried as end-to-end ciphertext over TURN across networks.

What WeTransfer does well

WeTransfer's core idea is asynchronous: the sender uploads once, gets a link, and the recipient downloads later. The two people never have to be online at the same time, which is exactly what you want when you email a video to a client who will open it tomorrow.

It is also mature and frictionless. There is nothing to install, the free tier lets you send without an account, and the interface is famously simple. For occasional link sharing within its size limit, it just works.

Where they differ: the file lives on a server

With WeTransfer, your file is uploaded to its servers, stored there for a while, and downloaded from there. The free tier caps each transfer at 2 GB, and the link points at a copy sitting on infrastructure you do not control. The transfer is encrypted in transit and at rest, but it is not zero-knowledge: the service holds the keys and could, in principle, read the file.

Relayium's realtime mode does not keep a server-side file copy or transfer history, so there is no server-side size cap to hit. On the same LAN the browsers connect directly; across networks they use a TURN relay by design, which carries end-to-end encrypted ciphertext but cannot read or decrypt the plaintext. On top of WebRTC, Relayium adds its own layer: an X25519 key exchange derives a key for per-chunk AES-256-GCM, both devices compare a matching 6-digit verification code (SAS) out of band to detect substituted endpoint public keys or endpoint impersonation, and each file is checked end-to-end with a SHA-256 hash.

Realtime transfers with no size cap

Because realtime mode keeps no server-side file copy or history, the practical file-size limit comes from your own browser. In Chrome or Edge, Relayium streams incoming data straight to disk, so there is effectively no size cap — multi-gigabyte videos and project archives are fine.

Firefox and Safari don't offer that same File System Access streaming, so when no streaming path applies the browser holds the file in memory instead; Relayium warns above roughly 256 MB, a deliberately conservative estimate rather than a measured hard limit. On the same LAN, realtime transfers need no account and the two devices connect directly: open relayium.com on both, pick up to 1,000 files, verify the code, and send. Across networks, whoever creates the pairing code signs in and the browser session uses an encrypted TURN relay by design; whoever joins with the code or link needs no account. TURN carries end-to-end encrypted ciphertext but cannot read or decrypt the plaintext. If a connection drops mid-way, the transfer resumes instead of starting over.

When the recipient is offline: zero-knowledge stored links

Realtime transfer needs both people present, which is the one thing WeTransfer's link model does better. So Relayium offers the same async convenience without giving up privacy: a stored download link.

Your browser encrypts the files with AES-256-GCM before upload, and the decryption key lives only in the URL fragment — the part after the # that browsers never send to the server. The server therefore stores zero-knowledge ciphertext it cannot read, and the recipient does not need an account to download. Creating such a link requires the sender to sign in, and each link can be set to expire or to burn after the first download.

Feature comparison at a glance

The differences that matter most, side by side:

Frequently asked questions

Is there really no file-size limit?

In realtime mode there is no server-side cap because Relayium keeps no server-side file copy or history. Same-LAN browsers connect directly; cross-network sessions carry end-to-end ciphertext over TURN. Chrome or Edge can stream realtime files to disk, but both live pages must remain active, so large files are better sent with a stored download link. Stored links have a per-file limit and account quota shown before upload; Firefox or Safari warns above roughly 256 MB for a realtime receive buffered in memory.

What if the recipient isn't online?

Use a stored download link. Your browser encrypts the files with AES-256-GCM, the key stays only in the URL fragment, and the server keeps zero-knowledge ciphertext the recipient can fetch later. Creating the link requires the sender to sign in, and you can set it to expire or burn after the first download.

Is Relayium free?

Yes. Relayium is free and open source under the AGPL-3.0 license, with the full protocol and code at github.com/relayium/relayium. There is no paid tier to unlock larger realtime transfers — the size headroom comes from streaming to disk in the browser, not from a subscription.

For a large file, leave an encrypted download link; for a quick small file or text, connect both sides and send it live.

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