A fax API service is an online fax account with a programming interface, so that a billing system, a records application or an internal tool can send a document as a fax and receive inbound faxes as files without a person opening a web page. The vendor still does the telephony; the developer sends an HTTP request. The Fax Line Index groups the vendors whose sites document an API into the fax API class and records each one's printed entry price, page allowance and overage, because those figures decide the running cost of an integration long after the code is written.
What an API fax integration does
The integration calls the vendor's endpoint with a destination number and a document, and the vendor returns a job identifier and later a status: delivered, busy, failed. Inbound faxes arrive as a callback or a poll, with the pages as a PDF or TIFF and the sender's number as metadata. That is the whole interface, and it is why fax survives inside software that nobody would design today: an insurer's claims system or a pharmacy's ordering system already produces the document, and the API turns a print step into a call. The developer's work is error handling, retries on a busy line, and storing the delivery report where the business can find it.
The class, and the printed prices
The index lists eFax, iFax, Fax.Plus, Documo and WestFax in the fax API class on the API pages their own sites publish. The entry prices are the same accounts a person would buy: Fax.Plus prints Basic at $6.99 a month with 200 pages and $0.10 per extra page; iFax prints Basic at $12.49 with 200 pages; eFax prints a starting offer of $14.99 with 500 pages and $0.07 per page over the plan; WestFax prints $14.99 billed monthly with 500 pages and a 3¢ overage; Documo prints $25 a month billed annually with 300 pages and $0.15 per additional page. API access on some vendors is a tier above the entry plan, and the developer should read the plan card for the word API before choosing on price.
What a fax API HIPAA plan adds
If the documents carry protected health information the integration makes the vendor a business associate exactly as a web account would, so the developer's employer needs a signed BAA for the plan and the code needs to respect it: pages fetched through the API should be stored encrypted, deleted from the vendor on the schedule the policy sets, and never written to a log. WestFax prints a signed BAA on every plan, which includes its API customers; eFax's Business plan card prints HIPAA compliance with a Business Associate Agreement. The cloud fax API vendors that also sit in the HIPAA class, iFax, Fax.Plus, Documo and WestFax, are the ones to shortlist when the payload is a medical record.
Questions people ask about fax api service
Do fax APIs charge per page or per month?
Both: a monthly plan with an allowance and an overage per page beyond it. Fax.Plus prints $0.10 per extra page, Documo $0.15, eFax $0.07 and WestFax 3¢. High-volume senders should price the overage first.
Can an API receive faxes too?
Yes. Inbound faxes to the account's number arrive as a webhook or can be polled, with the pages as a file. Every plan in the class includes at least one number.
Is a fax API HIPAA compliant by default?
No. The vendor must sign a BAA for the plan, and the integration must handle the pages as protected health information. The vendor's statement is on its pricing page; the index quotes it.