API

Detailed Explanation

API (Application Programming Interface) is a set of rules that lets different software applications communicate. When you check the weather on your phone, the app sends an HTTP request to a weather API, which sends back the data as JSON. APIs are everywhere: logging in with Google via OAuth, processing payments with Stripe, fetching posts from Supabase.

APIs work through endpoints — specific URLs that handle requests. A REST API is the most common style, using standard HTTP methods (GET, POST, PUT, DELETE) to perform CRUD operations. Your frontend calls APIs to get data from the backend, often using Async/Await and Promises. API keys authenticate requests.

APIs connect to databases, handle Authentication, power Edge Functions, define routes, and manage state in React apps. Claude Code helps you integrate APIs, and tools like caching, payloads, CORS, destructuring, JWTs, and Next.js all interact with API layers.