Design and build REST APIs the way real backends do — resources and URLs, HTTP methods and status codes, JSON shapes, input validation, errors, pagination, versioning, and OpenAPI docs. The hands-on examples use Next.js Route Handlers.
This course builds REST APIs with Next.js Route Handlers, so you should be comfortable writing JavaScript and reading JSON. You do not need any frontend or React knowledge — every example runs on the server.
Before you start
To practise, install VS Code and Node.js, open VS Code's integrated terminal (Ctrl+`), then scaffold and run a Next.js app with whichever package manager you use:
pnpm
pnpm create next-app@latest my-api
cd my-api
pnpm devnpm
npx create-next-app@latest my-api
cd my-api
npm run devAccept the defaults (App Router, TypeScript) so the examples match. Your API routes live under app/api/ — for example app/api/users/route.ts answers /api/users.
What Makes an API RESTful
Understand REST in plain words — an API is a way for programs to talk over the web. Learn what a resource is, why URLs should be nouns, and why every request stands on its own (stateless).
HTTP Methods & Status Codes
The verbs and the answers of an API. Learn when to use GET, POST, PUT, PATCH, and DELETE, what "safe" and "idempotent" mean, and which status code (200, 201, 400, 401, 404, 500) to return.
Designing JSON Responses
Shape the JSON your API returns so clients can trust it. Consistent field naming, ISO dates, string IDs, and a predictable shape for both single items and lists.
Building Endpoints with Route Handlers
Write a real REST endpoint in Next.js. Create a Route Handler in app/api, return JSON with Response.json, read a dynamic [id] from the URL, and handle GET and POST.
Validating Input
Never trust data from the client. Validate request bodies and query parameters, reject bad input with a clear 400, and use a schema library like Zod to keep it tidy and typed.
Errors, Pagination & Filtering
Polish your API for real use — return errors in one consistent shape, page through long lists instead of returning everything, and let clients filter and sort with query parameters.
Versioning & Documenting with OpenAPI
Keep your API stable as it grows. Version it so changes do not break existing clients, then describe it with an OpenAPI spec that doubles as living documentation.