RESTful APIs follow architectural principles to provide scalable and maintainable web services.
REST (Representational State Transfer) is an architectural style for designing networked applications. RESTful APIs follow a set of principles that make them scalable, maintainable, and easy to understand.
Resource-Based: Everything is a resource (users, products, orders) identified by URLs. For example, /users/123 represents user with ID 123.
Standard HTTP Methods: Use GET to read, POST to create, PUT/PATCH to update, DELETE to remove resources.
Stateless: Each request contains all information needed to process it. The server doesn't store client state between requests.
Client-Server Separation: Frontend and backend evolve independently as long as they agree on the API contract.
When building an e-commerce application:
GET /products retrieves all productsGET /products/42 retrieves a specific productPOST /products creates a new productPUT /products/42 updates product 42DELETE /products/42 removes product 42The HTTP method tells the server what operation to perform, and the URL identifies which resource to act on.
Simplicity: Uses familiar HTTP protocols that every web developer understands.
Cacheability: GET requests can be cached by browsers and CDNs, improving performance.
Scalability: Stateless nature makes it easy to distribute load across multiple servers.
Flexibility: Works with any data format (JSON, XML, HTML), though JSON is most common today.
REST APIs communicate results through standard HTTP status codes:
Use Nouns, Not Verbs: URLs should represent resources (/users) not actions (/getUsers).
Versioning: Include API version in URLs (/api/v1/users) to maintain backward compatibility.
Filtering and Pagination: For large datasets, support query parameters like /products?category=electronics&page=2.
Consistent Naming: Use plural nouns (/products, not /product) and maintain consistent conventions.
Stripe's payment API is a excellent example of RESTful design. Creating a payment involves POST /v1/charges with payment details, while retrieving payment history uses GET /v1/charges?customer=cust_123. Each endpoint is intuitive, and the HTTP methods clearly indicate the operation.
While REST dominates, alternatives exist:
REST remains the go-to choice for most public APIs due to its simplicity and universal understanding.