What is API (Application Programming Interface)?

An Application Programming Interface defines how software components should interact. REST APIs use HTTP methods (GET, POST, PUT, DELETE) to perform operations on resources identified by URLs. GraphQL APIs provide a query language letting clients request exactly the data they need. APIs are the backbone of modern software architecture, enabling microservices, third-party integrations, and mobile app backends. At Attreides, we design APIs using OpenAPI specification, implement them with Node.js or Python (FastAPI), and ensure they are well-documented, versioned, rate-limited, and secured with authentication.