What are some alternatives?
Postman - Postman is the most efficient way to test, develop and document APIs.
GitBook - Modern Publishing, Simply taking your books from ideas to finished, polished books.
Apigee - Intelligent and complete API platform
ReadMe - A collaborative developer hub for your API or code.
Gravitee.io - Gravitee.io is a flexible, lightweight and an open source API management solution.
ReadTheDocs - Spend your time on writing high quality documentation, not on the tools to make your documentation work.