API-first is a method in IT system design to connect system components with interfaces the so-called APIs (Application Programming Interfaces). A system is first designed in terms of its basic structure, components and dependencies, which is done downstream in integrated systems.

API-first is also used in the IT concepts of best-of-breed or microservices.

Transfer standards

Various methods are used to develop the APIs, such as REST (Representational State Transfer) or GraphQL (Graph Query Language). The most important communication protocol is HTTPS.

Data formats

Data formats and markup languages are used to transfer the content, usually XML, HTML, YAML (YAML Ain't Markup Language) or JSON (JavaScript Object Notation).