Send a file as an encrypted link
When the other side isn't online, upload now and share a link. Your browser encrypts before upload; the server keeps only ciphertext it can't read — the key never leaves the link.
How the link is made
- Sign in and pick a file — your browser encrypts it locally before anything leaves the device.
- The server stores only the ciphertext; the decryption key stays in the link fragment and is never sent to the server.
- Share the download link (optionally burn-after-read, with an expiry you choose).
- The recipient opens the link; their browser fetches the ciphertext and decrypts it with the key from the link.
Why send it this way
- Zero-knowledge — The file is encrypted in the browser; the server only ever holds ciphertext it cannot decrypt.
- Key in the link — The decryption key lives in the URL fragment (after #), which browsers never send to the server.
- Burn-after-read + expiry — Optionally delete the file on first download, and set a time-to-live after which it's gone.
- No recipient account — Anyone with the link can download; only the uploader needs to sign in.
- Async complement — Use this when the other side isn't online right now; use realtime cross-network transfer when both are present.
Compared with the alternatives
vs WeTransfer / Dropbox links
Those can read your files server-side; Relayium's server only holds ciphertext it can't decrypt — the key stays in the link.
vs realtime mode
Realtime needs both sides online at the same time; this stores the file encrypted so the recipient can fetch it later.
Frequently asked questions
Can the server read my file?
No — it's encrypted in your browser; the server stores only ciphertext and the key never reaches it.
Where is the key?
In the link's fragment (after #). Browsers don't send fragments to servers, so only someone with the full link can decrypt.
Do I need an account?
To upload, yes (it uses storage). To download, no — just the link.
Can I make it one-time?
Yes — enable burn-after-read, and set an expiry.
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