API Version and Access Guidance
The main Sent Faxes and Received Faxes documentation uses /api/v3 for the linked organization’s native web fax workflow. V3 requires successful self-serve activation (where offered for your account) or coordinated enterprise enrollment before using live credentials or test keys for simulated sends. Signup and a new key do not grant access automatically.
Web Fax API v3: activation and enrollment
Activated self-serve developers and enrolled enterprise customers can use the v3 fax API to work with their organization’s native web fax documents. V3 requires an explicit organization link and production-access eligibility. Live keys support real fax operations; test keys support simulated sends, sent-fax listing, polling, downloads and callbacks. Received-fax operations require live keys. Where self-serve is offered for your account, verify email, complete the BAA, choose your number and add a card; successful activation links your organization and configures sender attribution automatically. Enterprise and manual integrations coordinate enrollment, organization access and sender attribution with Medsender. Existing integrations keep their v2 routes and keys; changing the URL alone does not migrate fax history or grant access.
Legacy API v2
Existing integrations use https://api.medsender.com/api/v2 and the Legacy API (v2) references. The OpenAPI description and legacy endpoint catalog cover v2. Keep the v2 URL for those workflows; changing it alone does not enroll an account or migrate history.
Test and live credentials
API requests authenticate with a Bearer API key. Test keys begin with sk_test_ and keep development activity separate from live keys, which begin with sk_live_. Send the selected key in the Authorization: Bearer YOUR_API_KEY header. The same authentication shape is declared in OpenAPI so generated tools know that credentials belong in the HTTP Bearer header.
After signing in to the developer portal, open the API Keys area to create and manage the keys available to your account. After enrollment, use the v3 simulated-send guide with a test key. Existing v2 integrations use the legacy v2 test quickstart. Read the authentication guide before making the first request.
Access help and documentation questions
If an account does not show the key access needed for a documented workflow, or if an example does not match an observed response, contact support@medsender.com. Include the documentation page, HTTP method and path, whether a test or live key was used, and the request identifier when one is available. Do not include an API key, patient document, or other sensitive payload in a support message.