eFax Developer fax alternative
eFax Developer offers the REST-based Enterprise API and the older Universal Outbound XML interface. Both are covered here. mintfax is an outbound fax API with public documentation, published per-page rates, and registration through the API.
Feature comparison
| Feature | eFax Enterprise API (Universal Outbound noted where they differ) | mintfax |
|---|---|---|
| API style | REST/JSON (Universal Outbound: XML in application/x-www-form-urlencoded POST) | REST/JSON |
| Production auth | OAuth 2.0 bearer tokens from AppID + API Key | Bearer token in Authorization; keys do not auto-expire |
| Environment scoping | Per-AppID isolation; separate AppID for DEV, QA, PROD | Environment inferred from key prefix (mfx_test_, mfx_live_, mfx_acct_) |
| Signup | Through sales (Welcome email dispatched by a Sales Engineer) | POST /account/register plus a 6-digit verify code |
| Public per-page price | Not published for the Enterprise API | $0.060 standard; $0.048 at 100,000+ pages/mo; $0.036 at 1,000,000+ pages/mo |
| BAA | Sales (“We Sign BAAs”); no published turnaround | Free BAA in the dashboard; separate DPA in the dashboard |
| Webhook signing | Optional HMAC (“can be set up to require”); algorithm and headers in customer portal | HMAC-SHA256 per Standard Webhooks; per-endpoint whsec_ secret; three headers |
| Idempotency on send | Not documented | Idempotency-Key header; 24h expiry; 409 idempotency_key_reuse |
| Send retries | “Custom retry schemes are available for number of retries and retry interval.” | Per-fax max_attempts 1-5; backoff 1m / 3m / 5m / 5m; default 3 attempts |
| Error model on send | In customer portal error catalogue | 17 API error codes plus 10 delivery error codes plus optional error_subcode |
| Request tracing | Not documented publicly | X-Request-Id: req_<ULID> on every response; echoed as request_id |
| Sandbox | Single demo fax number provisioned by sales | Nine test numbers for nine scenarios; same API as live |
| Public documentation | In customer portal; QSG marked “confidential and access-restricted” | Public OpenAPI 3.1, markdown docs, and error catalogue |
| File formats | Universal Outbound: Word, Excel, PDF, plain text, HTML, TIF (barcode support is a separate capability); Enterprise API: in customer portal | PDF, DOCX, XLSX, JPG, PNG, TIFF, HTML, plain text (8); 10 MB upload |
| Inbound / receive | Yes (GET /faxes/received, PDF or TIFF, fax-number provisioning) | No (outbound only) |
| Number porting / provisioning | Yes (Admin API “Number Management”) | Not offered |
| Barcode support | Universal Outbound: reading and generation; Enterprise API: not enumerated publicly | Not offered |
| HITRUST CSF certification | Yes (eFax Corporate) | No |
| SDKs | Universal Outbound: off-the-shelf Java and .NET / COM Object SDKs | No official SDK packages |
| Category | Full cloud-fax suite (SoHo tiers, Enterprise API, eFax Corporate) | Fax only |
Registration and pricing
The eFax Enterprise API setup process starts with API details supplied by a sales engineer. Its per-page prices are not published.
You can create a mintfax account through the API, verify your email, and begin testing without a credit card. Live delivery uses prepaid credits. The pricing page lists all three volume rates.
Documentation and webhooks
eFax’s public quickstart describes optional HMAC authentication for webhooks. The signing algorithm and header details are in its customer portal, along with the error catalogue.
mintfax publishes its API specification and error guide. Every webhook is signed using HMAC-SHA256 under the Standard Webhooks specification. The verification guide explains how your receiver checks the signature.
Testing
eFax supplies a demo fax number for sending and receiving during testing. mintfax provides nine sandbox test numbers for repeatable outcomes, including successful delivery, busy lines, and invalid numbers.
The mintfax sandbox uses the same API as live, with simulated payments and fax delivery. It is active before you buy credits.
Agreements
eFax signs BAAs through its sales process. mintfax offers a BAA and a separate DPA in the dashboard. An authorized signer can accept each agreement and download the signed PDF immediately. See compliance for the controls and their limits.
Other requirements
eFax supports receiving faxes, number management, and features such as barcode handling in Universal Outbound. It also provides Java and .NET / COM SDKs for that interface. mintfax sends faxes only and has no official SDK packages.
eFax Corporate holds HITRUST CSF certification. mintfax does not hold HITRUST, SOC 2, ISO 27001, or FedRAMP certification.
If you decide to switch, the eFax migration guide covers both Enterprise API and Universal Outbound.