The security model
Zero knowledge is optional and yours to switch on: turn on password protection and your files are encrypted before they leave your device, and the key never touches our servers. For those files we could not read them if we wanted to, were paid to, or were ordered to. Leave it off and the file is uploaded unencrypted, which our servers can read.
Stage What happens Who can access it
Select You pick files in your browser. Nothing has moved yet. Only you
Encrypt libsodium encrypts each chunk locally, with a key Argon2 derives from your password on your device. Only you
Upload Only ciphertext travels. TLS wraps it a second time in transit. Only you
Store Our servers hold your file blobs (ciphertext when you enable password protection, otherwise the plain file) plus metadata we can always read: filenames, folder names, size, timestamps, and a hash of the file's plaintext that lets us tell whether a specific known file was uploaded. You + metadata: us
Share The link carries no key. You pass the password separately, so a leaked link on its own decrypts nothing. Anyone with link + password
Download The recipient's browser fetches ciphertext and decrypts it locally, once they enter the password. Only you
Delete Blobs are unlinked immediately and scrubbed from storage in the next sweep. No one
Don't take our word for it. The whole thing is open source: read the encryption code yourself.