"Secure" usually means TLS plus a password field. Here it means the service physically cannot decrypt what you sent, because it never receives a key.
“Security you can verify by asking one question: what does the server actually hold?”
For professionals sending confidential deliverables, contracts, medical or legal documents and unreleased creative work.
Keys are derived on your device with Argon2id and never transmitted. There is no server-side key escrow and no recovery back door.
XChaCha20-Poly1305 means a tampered file fails to decrypt rather than silently opening as corrupted data.
Public links expire within 24 hours at most; you can shorten that, cap views or revoke immediately.
For material that should be read rather than kept, per-recipient watermarking identifies the source of a screenshot.
Creation, access and revocation events recorded without recording content.
No AI classification, no human review queue, no advertising business built on what you send.
In transit (TLS) protects the network, not the vendor. At rest protects against a stolen disk, while the service still decrypts on demand. Client-side, zero-knowledge encryption means the plaintext never exists outside sender and recipient devices. Only the third level changes who can read your file.
Many transfer services offer a password on the download page. That is an access check performed by a server that already holds your readable file. A passphrase in a zero-knowledge system participates in deriving the key: without it, there is nothing to serve, not even to the operator.
What exactly does your server hold when I upload? Can any employee produce the plaintext, under any process? Is the download password an access check or part of the key derivation? Do links expire automatically? A vendor that answers precisely is telling you something useful either way.
No, and that is the guarantee working as intended. We hold ciphertext with no key. Keep your Recovery Kit offline.
We cannot: there is nothing readable to scan. Recipients should keep their own endpoint protection, exactly as they would for any download.
No. Files are encrypted on your device with XChaCha20-Poly1305 before the upload starts, using keys derived locally with Argon2id. Our servers hold ciphertext only, so there is no preview, no scanning and no staff view of your transfer.
No. They open the link in any browser, type the passphrase you shared separately, and the file is decrypted locally on their machine. Nothing to install, nothing to sign up for.
Public share links always expire within 24 hours at most, and you can make them shorter, limit the number of views, or revoke them instantly. Expiry is enforced by the system, not by a reminder.
Uploads are chunked, resumable and verified after upload, so multi-gigabyte transfers survive a dropped connection, a closed laptop or a hotel network. You resume instead of starting again.
Yes. The free plan includes 1 GB with exactly the same zero-knowledge architecture as paid plans, so you can test a real client hand-off before paying anything.
Because we cannot read your data, we cannot reset it for you. Each account creates a Recovery Kit — a printable PDF with a QR code — to store offline. That is the same property that keeps anyone else, including us, out of your account.
Start free with 1 GB. Zero-knowledge encryption from the first upload — no admin override, no AI scanning, no plaintext on the server.
