What are some alternatives?
When comparing Apiary and ReadMe, you can also consider the following products
Postman Collections - Biggest library of ready-made API collections for Postman
ReadTheDocs - Spend your time on writing high quality documentation, not on the tools to make your documentation work.
Gravitee.io - Gravitee.io is a flexible, lightweight and an open source API management solution.
GitBook - Modern Publishing, Simply taking your books from ideas to finished, polished books.
Apigee - Intelligent and complete API platform
Docusaurus - Easy to maintain open source documentation websites