

That can be developed using an API definition languageĪn API first approach seems to want to focus first on the API rather than building versions of the API for mobile and web etc. In an ecosystem of API's, one would like the API's to have a level of consistency

They seem to state some characteristics of API that are developed using an API First approach: It involves planning across stake holders and feedback on the API before the API is translated to code. API first approach involves giving more thought ahead of time toward the design of the API. Swagger.io defines API first as: " An API-first approach means that for any given development project, your APIs are treated as “ first-class citizens.” That everything about a project revolves around the idea that the end product will be consumed by mobile devices, and that APIs will be consumed by client applications.". The term API First design seems to be quite prevalent with Microservices and especially for those on the cloud.
