API-first development involves designing and building an application programming interface (API) before the rest of the application, treating each API as a product unto itself rather than a communication layer to be built later in the software development lifecycle. This strategy focuses on building the API first, then adding a user interface to it, which results in a more flexible and easy-to-use API that makes it easier to build out a robust microservices architecture. An API-first approach allows developers to work with the same data and functionality through both the backend and frontend, enabling tasks such as syndication, migration, and complex data manipulation to be automated without repetitive manual work. By considering all possible uses and endpoints early on, an API-first app can provide clear technical documentation and supportive tooling like software development kits (SDKs), making it easier for developers to accomplish their goals and fuel business digital transformation.