Is online fax secure?
Oh Fax encrypts documents in transit and at rest and deletes them 24 hours after the fax finishes, but fax lines themselves are not encrypted end to end and Oh Fax is not for patient data (PHI).
Updated October 28, 2026.
The short answer
Your upload to Oh Fax travels over HTTPS and is stored encrypted. We delete the document 24 hours after the fax reaches a final state and keep only a record of the transaction (destination, page count, timing and a content hash). The last leg is an ordinary fax call to the recipient's machine, and anyone near that machine can read the pages.
- Price: $2.00 per fax by card, for a PDF of up to 100 pages and 25 MB. No account and no subscription.
- Where: fax numbers in the US and Canada only.
- Send-only: Oh Fax sends faxes. It cannot receive faxes or give you a fax number.
- Not for patient data: do not use Oh Fax for protected health information (PHI).
- Refund: if the fax cannot be delivered, you get a full refund and the reason.
What to check before you fax
- Confirm the number with the recipient. A wrong number sends your pages to a stranger.
- Ask whether the recipient uses a shared fax machine.
- Don't use Oh Fax for medical records or other protected health information. Our terms do not allow it.
Compared with other options
| Service | One 10-page fax without a plan | Monthly plan needed | Account needed |
|---|---|---|---|
| Oh Fax | $2.00 by card (any fax up to 100 pages) | No | No |
| Dropbox Fax | $0.99 per fax up to 10 pages, after 5 free pages (details) | No | Yes |
| WiseFax | $10.00 (one $1.00 token per page; a 1-page fax is $1.00) (details) | No | Yes |
| FaxZero Premium | $3.29 per fax up to 25 pages (details) | No | No (email required) |
| eFax | Not offered; eFax sells monthly plans (details) | Yes; eFax lists a 200-page plan, and its page did not show the dollar price when we checked | Yes |
Services that handle PHI usually require a business associate agreement on a paid plan. Oh Fax does not offer one. Details: Limits and Privacy.
FAQ
Does Oh Fax keep my document?
No. It is deleted 24 hours after the fax reaches a final state. We keep a record of the fax, not its contents.
Can I fax medical records with Oh Fax?
No. Oh Fax is not designed for protected health information (PHI).
Is faxing more secure than email?
Neither is end-to-end encrypted to the recipient. Fax goes over the phone network to one machine, so the main risks are a wrong number and who can see the recipient's machine.