RESTful API Modeling Language (RAML)

RESTful API Modeling Language (RAML) is a YAML-based language for describing RESTful APIs

http://en.wikipedia.org/wiki/RAML_%28software%29

RESTful API Modeling Language (RAML) makes it easy to manage the whole API lifecycle from design to sharing. It's concise - you only write what you need to define - and reusable. It is machine readable API design that is actually human friendly.