Apiary provides a free tier of the platform which allows a small group of developers to collaborate easily on the design of open source APIs. In addition to this, it provides mock endpoints allowing people to experiment with the API without depending or having to stand up a real backend. With our clients, using Apiary allows us to very quickly pull together an API definition (particularly when using API Blueprint). The whole API design process for the simpler use cases can be done in a relatively short workshop which makes it a lot easier to agree, publish, version-manage an API definition with suitable documentation. This can then be evolved and enhanced (particularly in the documentation aspects). With the ability to support Swagger (Open API v2 and introducing/ed support for v3) and API Blueprint makes it a very versatile tool.
