The short answer
Your document reaches us over HTTPS and is erased from our servers once the fax is sent. The final leg is different: the phone line to the recipient's fax machine isn’t encrypted, and that is the case for every fax, whoever sends it.
So the service takes care of its side, and the rest depends on precautions on yours. The security page explains them, and the fax over IP article describes what happens on the line.
What is protected
The file moves between your browser and our servers over HTTPS, which keeps it unreadable in transit. After the send, we delete the document from our servers. Stripe handles payment, so your card number never passes through us.
Data protection follows European rules, as the service is operated from France. The privacy page tells you what is processed and why.
What cannot be encrypted
A fax ends with a phone call to a fax machine. That call is not end-to-end encrypted, whichever service placed it. Pages then come out of a printer, where anyone in the room may read them.
Part of the route may run as IP traffic between operators; the fax over IP article explains how that works and why it does not change the picture for the last leg.
Sensible precautions
Check the number, check it again and, for anything delicate, call the recipient so that they wait next to the machine. Remove pages and data that are not needed. Use a cover sheet that asks for the pages to be given only to the addressee.
If your obligations require end-to-end encryption, choose a different channel for that document. The security page gives a fuller checklist.
Worth remembering
- Upload over HTTPS; file deleted from our servers after sending.
- The phone leg to the recipient is not encrypted, for any fax service.
- Verify the number and warn the recipient when content is sensitive.