What are some alternatives?
When comparing Apiary and GitBook, you can also consider the following products
Postman Collections - Biggest library of ready-made API collections for Postman
Visual Studio Team Services - Visual Studio Team Services (VSTS) provides unlimited Git hosting, cloud build for CI, agile planning and continuous delivery.
Gravitee.io - Gravitee.io is a flexible, lightweight and an open source API management solution.
Atlassian Bitbucket Server - Atlassian Bitbucket Server is a scalable collaborative Git solution.
Apigee - Intelligent and complete API platform
GitHub Desktop - GitHub Desktop is a seamless way to contribute to projects on GitHub and GitHub Enterprise.