A HIPAA-Compliant Cloud Fax API, Built Into Your Product
Documo's cloud fax API lets your platform send and receive fax with one REST call and a webhook. Your customers stay in your product, and you never build or run fax infrastructure.
curl -X POST https://api.documo.com/v1/faxes \
-H "Authorization: Basic YOUR_API_KEY" \
-F "faxNumber=12345678900" \
-F "attachments=@referral.pdf"import fs from "node:fs";
const form = new FormData();
form.append("faxNumber", "12345678900");
form.append("attachments", new Blob([fs.readFileSync("referral.pdf")]), "referral.pdf");
const res = await fetch("https://api.documo.com/v1/faxes", {
method: "POST",
headers: { Authorization: "Basic YOUR_API_KEY" },
body: form,
});
console.log(await res.json());import requests
with open("referral.pdf", "rb") as f:
res = requests.post(
"https://api.documo.com/v1/faxes",
headers={"Authorization": "Basic YOUR_API_KEY"},
data={"faxNumber": "12345678900"},
files={"attachments": ("referral.pdf", f, "application/pdf")},
)
print(res.json())Ruby and PHP samples are in our Postman collection.
Your customers' document work is happening outside your product
Referrals, prior auths and records still arrive by fax. If your platform can’t handle them, users leave it to do the paperwork elsewhere.
62%
of healthcare professionals say more than a quarter of their document work happens outside the EHR.
48%
say document delays often or always affect patient care.
18%
are investing in document workflow automation today. The rest is open ground for your product.
Source: Documo, 2026 State of Healthcare Operations
Trusted by Healthcare Organizations and the Platforms That Serve Them
Outcomes for Your Product, Not Just a Fax Endpoint
Keep Users Inside Your Platform
Fax sending, receiving and status happen in your interface, so customers stop switching to a separate portal or fax machine.
Get Inbound Faxes as Events
Every received fax triggers a webhook to your endpoint, so your app can file, route or display it the moment it arrives.
Ship Without Building Fax Infrastructure
Skip carrier connections, number provisioning, retries and delivery tracking. Your engineers build product features instead.
Pass Security Reviews With Your Customers
HIPAA BAA, SOC 2 Type II and HITRUST e1, with fax activity, delivery status and metadata logged for audits.
For Developers
How the Cloud Fax API Works
Ruby and PHP samples are in the Postman collection.
Get API Keys
Test everything in the sandbox before you go live.
Send Faxes
Call POST /v1/faxes with a faxNumber and your document. Send up to 180 requests a minute, or use fax blast to send one document to many recipients.
Receive Faxes
Each inbound fax arrives at your webhook as fax.v1.inbound.complete. If your endpoint misses it, Documo retries up to 8 times. Secure your endpoint with Basic auth or OAuth 2.0.
Build or Integrate
Build Your Own Fax Infrastructure, or Use a Fax API
Carrier Connections and Fax Numbers
Build it Yourself
Source, provision and maintain carriers.
With Documo
Included, with number provisioning and porting by API.
Delivery, Retries and Status
Build it Yourself
Engineer retry logic and monitor it.
With Documo
99.8%
delivery rate.
Uptime and On-Call
Build it Yourself
Your team carries the pager.
With Documo
99.9%
uptime SLA.
Security and Compliance
Build it Yourself
Run audits and maintain controls.
With Documo
HIPAA compliant with a BAA.
SOC 2 Type II and HITRUST e1 certified.
Webhook Delivery
Build it Yourself
Build queuing, retries and endpoint auth.
With Documo
Up to 8 retries with backoff. Basic auth or OAuth 2.0.
Audit Trail
Build it Yourself
Design, store and retain logs.
With Documo
Logged by default.
Why Healthtech Teams Build on Documo's API
We needed fax to live inside our own systems, not a separate portal our team had to manage. Documo's API gave us the programmatic control to build fax directly into our workflows.
3,000 to 4,000
inbound faxes a day through the API.
No
on-premises fax servers to maintain.
Jason Riddle
CTO, Regalo Health
We realized fax is still the way to go in this industry. So instead of buying a fax machine, we decided to implement a service that would input fields programmatically from the EMR into a PDF and fax it off.
Levi Hamilton
VP of Product, Lumeca Health
The APIs
Fax API and IDP API
Send and receive fax with the Fax API. Turn inbound documents into structured data with the IDP API, now in early access.
Fax API
Send, receive and track HIPAA-compliant fax from your product, including fax blast and inbound webhooks.
Base URL
https://api.documo.com/v1
Auth
Basic YOUR_API_KEY
Webhook
fax.v1.inbound.complete
IDP API
Early accessSplit multi-document files, identify each document's type and pull out field values. IDP endpoints are available in Documo's early access API.
Webhooks
idp.v1.split-detection.completed
idp.v1.document-type.updated
idp.v1.document-field-value.assigned
Direct Secure Messaging
BetaSend and receive Direct messages with C‑CDA attachments to providers on the Direct network.
Base URL
api-dsm.documo.com
Auth
Bearer token from POST /dsm/token
Everything You Wanted to Ask About Our Cloud Fax API
Can’t find an answer? Check our Help Center or email us.
What is a cloud fax API?
A cloud fax API lets your software send and receive fax over HTTPS instead of through fax machines, phone lines or an on-premises fax server. Documo runs the carrier connections, fax numbers, delivery and retries, so your application makes REST calls and listens for webhooks.
How do I send a fax with an API?
Call POST https://api.documo.com/v1/faxes with your API key, the destination faxNumber and your document as attachments. The response returns a message ID you can use to track the fax, and an outbound webhook tells your app when delivery completes.
Can I white-label fax inside my product?
Yes. Your customers send, receive and track fax in your own interface, so they never see a separate Documo portal. If you want to resell a fully branded fax service, the Documo Partner Program covers white-label options.
How do I receive faxes with the API?
Register a webhook for inbound fax events. When a fax arrives on one of your numbers, Documo posts the fax details to your endpoint, and your app downloads the document by its message ID. You can secure the endpoint with Basic auth.
Does Documo have an IDP API?
Yes. The IDP API splits multi-document files, identifies each document type and extracts field values, with webhooks such as idp.v1.split-detection.completed when results are ready. IDP endpoints are in Documo’s early access API.
Is there a rate limit?
Yes. Sending faxes allows 180 API calls per minute per API key, and most other endpoints allow 60. Every response includes rate limit headers that show how many calls you have left. To send one document to many recipients, use fax blast.
Is there a sandbox?
Yes. The sandbox is a copy of the Documo app with its own API at api.sandbox.documo.com. It doesn’t send real faxes, so you can test sending, receiving and webhooks before you go live.
Which languages have code samples?
This page shows cURL, Node.js and Python. Ruby and PHP samples are in the Postman collection, and the API docs can generate snippets for many other languages and libraries.
Is Documo's fax API HIPAA compliant?
Yes. Documo signs a Business Associate Agreement (BAA) and is SOC 2 Type II and HITRUST e1 certified. Faxes are encrypted in transit and at rest, and fax activity is logged for audits.
How does the API support audits?
The API logs fax activity, delivery status and metadata for every fax. Your team can pull fax history and reports through the API, so audit requests don’t depend on manual records.
Can the API handle high volume?
Yes. Regalo Health runs 3,000 to 4,000 inbound faxes a day through the API. The send endpoint accepts 180 requests a minute, fax blast sends one document to many recipients, and the platform carries a 99.9% uptime SLA.
Put Fax Inside Your Product
sandbox access and your integration.