Kostet
Kostet secure transfer

Send documents securely

Your documents are encrypted on this device before they are sent. No account, password, or software installation is required.

Encrypted locally Ciphertext-only storage Automatic deletion

Your details

Optional. These fields are encrypted together with your documents.

All fields optional

Documents

Select one or more files. Their original names are also encrypted.

Drop files here or

    Encryption starts only after you press Send.

    How is this secure?

    The page packages your documents, message, contact details, and original filenames, then encrypts everything in your browser with Kostet’s public key. The server receives and stores only the encrypted package. The private decryption key is held separately and is not on this web server.

    What information can the server see?

    The server sees a random submission reference, reception time, encrypted size, and normal security logs. It cannot see document contents, original filenames, your message, or the optional contact details.

    Need higher assurance?

    Encrypt sensitive material with Kostet’s published age recipient before opening this page. You can then upload the already encrypted .age file below.