What is REST API?

What is a REST API?

REST API is an API design style that models data as resources and exposes those resources over HTTP. For example, /customers/42 can represent one customer, while /orders can represent a collection of orders.

In REST, HTTP methods carry meaning: GET reads data, POST creates a new record, PUT or PATCH updates it, and DELETE removes it. Responses are usually JSON, while outcomes are expressed through HTTP status codes such as 200, 201, 400, 401, and 404.

REST API Design Basics

• Stateless requests: The server should be able to evaluate each request independently.
• Consistent resource names: URLs should describe resources, not actions.
• Versioning: Breaking changes need a strategy such as /v1.
• Pagination and filtering: Large lists should be split into controlled pages.
• Error model: API consumers should receive machine-readable error details.

Business Use

REST APIs are used to connect mobile apps to backends, link e-commerce platforms with shipping and payment providers, integrate ERP/CRM systems, and expose internal data to partner applications. Because REST uses standard HTTP infrastructure, monitoring, testing, and documentation tooling is mature.

REST is not the best choice for every integration. If clients need highly flexible data selection, GraphQL may fit better. If systems should notify each other when an event happens, a Webhook may be simpler. The broader API concept includes REST as one design option.

At Barlas Dijital, REST API design is often central to API development and integration projects.