1) The best tool is probably RAML. It's very succinct, looks like YAML and has powerful features such as traits that really simplify the process of documenting

1) The best tool is probably RAML. It's very succinct, looks like YAML and has powerful features such as traits that really simplify the process of documenting many endpoints with similar traits (e.g. pagination). http://raml.org/ http://raml.org/ 2) Swagger is an older option that is quite verbose but has a lot of good tooling support. 3) A third tool that is pretty decent is API blueprint. Disclosure: I did work on an open source swagger-raml converter about four months ago.