A developer portal is the interface between a set of APIs and their various stakeholders. The portal can play several roles to achieve the business goals of an organization.
A lot of API teams publish their "Swagger" documentation and call it a developer portal. That is wrong on two accounts: the documentation format formerly known as Swagger is now called the Open API spec, and more crucially, reference documentation is only one part of the minimum viable developer portal.
Yes, your developer portal needs to contain API reference documentation (no matter what specification format you use) but a developer portal should also be a sort of self-service support hub, a trust signal, a communication nexus for API stakeholders and a key DevRel tool that helps an organization to provide the best possible developer experience for its APIs.
We’ve been working for a long time to capture what is the essence of a developer portal–and this infographic is our take. Does this match your view? We would welcome your feedback.