Two-factor authentication.
Delivered the old-school way.
2FA by Fax sends one-time passcodes to registered fax numbers instead of SMS, email, or push. No SIM swapping. No signal required. Just the reassuring hum of a machine that has never once been phished.
Median delivery: 11.4s · 99.99% line uptime · G3 + T.38 supported
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Three steps. One dial tone.
Register the number
Each user enrolls a verified fax number. We confirm the line with a test page and a handshake fingerprint stored against the account.
Call the API at login
One POST generates a six-digit passcode and queues the transmission. Our gateway dials, negotiates, and confirms receipt page by page.
Verify the page
The user walks to the machine, collects the sheet, and types the code. Codes expire in five minutes, whether or not toner cooperates.
Real security. Real reliability. Real satisfaction.
Stronger than SMS
No SIM swapping, no SS7 interception, no carrier support rep talked into a port-out on a Tuesday.
Fax-delivered OTPs
Six-digit passcodes printed on paper, delivered to a physical location you already control access to.
Offline reliability
Works when the internet doesn't. Copper holds up in outages, dead zones, and basement records rooms.
Built for organizations
Healthcare, legal, government, and finance teams with strict retention and compliance requirements.
Easy to integrate
A REST endpoint, a webhook, and SDKs for six languages. Drop-in replacement for your SMS provider.
Retro tech. Modern security.
The hum of a fax machine, the power of the future. Because security never goes out of style.
If your industry still runs on fax, your 2FA should too.
Every regulated workplace we've met already has a fax number, a fax log, and a person who guards both. We simply put your authentication factor where the paper trail already lives.
One endpoint. Then walk to the machine.
Send a challenge, verify a code, and subscribe to transmission webhooks — delivered, busy, no answer, out of paper. Sandbox lines are free and print to a virtual tray.
- SDKs for Node, Python, Go, Ruby, PHP, and .NET
- Cover-page templates with your own branding
- Signed webhooks with per-page delivery receipts
- Fallback routing to a secondary line after two busy signals
curl https://api.2fabyfax.com/v1/challenges \ -H "Authorization: Bearer $FAX_KEY" \ -d user_id=usr_10482 \ -d fax_number=+13125550148 \ -d cover_page=corporate_navy { "id": "chg_8Xf2c", "status": "dialing", "expires_in": 300, "pages": 1 }
Priced per page, like everything good.
Single Line
500 transmissions included
- 1 outbound gateway line
- Standard cover page
- Email support
Bonded Pair
POPULAR5,000 transmissions included
- Redundant lines with auto-failover
- Branded cover pages
- Webhooks and delivery receipts
- Priority support, 8am–8pm ET
Switchboard
Volume rates and dedicated trunks
- Dedicated T.38 trunk group
- On-prem gateway option
- Retention and audit exports
- Named support engineer
The people keeping the line open.
2FA by Fax was founded in a records room in 2019 on a simple observation: the most secure device in most offices is the one nobody has bothered to connect to the internet.
Marguerite Ashby
Spent eleven years running identity programs for regional hospital networks. Started 2FA by Fax after an audit found the fax log was the only tamper-evident record in the building.
Desmond Oyelaran
Former telecom engineer who has personally debugged more T.38 handshakes than he cares to count. Owns nine fax machines, four of which still work.
Priya Venkataraman
Built HIPAA and SOC 2 programs at two health-tech companies. Translates between auditors, attorneys, and engineers without raising her voice.
Hollis Brandt
Came up through enterprise support desks in insurance and logistics. Believes every escalation is really a question about paper, toner, or a busy signal.
Questions we get a lot
What if the machine runs out of paper?
The gateway receives an out-of-paper status from the receiving unit and fires a webhook so your app can offer a retry or a secondary line. Codes never expire early.
Isn't a printed code less secure than a phone?
It's a different threat model. Fax delivery trades remote attack surface for physical access control — which is exactly the trade regulated offices with badge readers want to make.
Do we need a physical fax machine?
No. Virtual fax endpoints and multifunction printers work fine. We do think the physical unit is more fun, and we will not be talked out of that position.
How long does delivery take?
Median 11.4 seconds from API call to transmission-complete, plus however long it takes your colleague to walk down the hall.
Because security never goes out of style.
Secure. Reliable. Fax-delivered. Start a sandbox line in about four minutes.