What is the main difference between a REST API and a Webhook?

A REST API requires a client to explicitly request data from a server, whereas a webhook automatically sends data to a client when an event occurs. In a REST system, the client initiates all communications. Webhooks operate on a push model where the server proactively pushes updates to a listener URL whenever a specific event triggers.

Does a REST API always use JSON?

No, a REST API does not strictly require JavaScript Object Notation (JSON), though it is the most common format. REST APIs can transfer data in various formats, including Extensible Markup Language (XML), Plain Text, or Hypertext Markup Language (HTML). The client and server specify the format using standard HTTP headers during the request and response process.

What does it mean for a REST API to be stateless?

A stateless REST API means that the server does not store any client session information between requests. Every individual request sent by a client must contain all the information necessary for the server to understand and process it. This design ensures that each request is processed independently, improving scalability and reliability across web servers.

Web Development

REST API

A Representational State Transfer Application Programming Interface (REST API) is an architectural style for web services where data resources are accessed through unique web addresses using standard web commands.

also called: RESTful API

// definition

A Representational State Transfer Application Programming Interface (REST API) is an architectural style for network-based software applications that exposes data and functions through structured web links. It relies on standard Hypertext Transfer Protocol (HTTP) operations such as GET, POST, PUT, and DELETE to perform actions on specific resources identified by unique addresses. Request and response payloads are typically formatted in plain text formats like JavaScript Object Notation (JSON) or Extensible Markup Language (XML).

Although frequently confused with generic web services or Remote Procedure Call (RPC) interfaces, a true REST API is stateless and resource-oriented rather than action-oriented. In an RPC system, a client executes remote functions directly, whereas a REST API allows clients to interact with data objects using standardized operations, decoupling the front-end application from backend processing logic.

// why it matters

Adopting a REST API allows an organization to separate its user-facing front-end software from its underlying database and backend processing code. Because REST APIs use standardized HTTP standards and stateless communication, developers can update or replace client applications, such as mobile apps or web portals, without altering the core server operations. Standardizing integrations around REST APIs enables third-party software applications to securely exchange data with company systems. This modular architecture reduces software integration costs, shortens development lifecycles for new digital features, and allows systems to scale independently as traffic demands increase.

// example

An e-commerce system uses a REST API to manage user orders. To retrieve order details for customer 102, a client application sends a GET request to https://example.com/api/orders/102. The server responds with a JSON payload containing details such as the order date, items purchased, and total price. To update the shipping address, the client sends a PUT request containing the new address data to that same URL.

Questions and Answers

What is the main difference between a REST API and a Webhook?: A REST API requires a client to explicitly request data from a server, whereas a webhook automatically sends data to a client when an event occurs. In a REST system, the client initiates all communications. Webhooks operate on a push model where the server proactively pushes updates to a listener URL whenever a specific event triggers.
Does a REST API always use JSON?: No, a REST API does not strictly require JavaScript Object Notation (JSON), though it is the most common format. REST APIs can transfer data in various formats, including Extensible Markup Language (XML), Plain Text, or Hypertext Markup Language (HTML). The client and server specify the format using standard HTTP headers during the request and response process.
What does it mean for a REST API to be stateless?: A stateless REST API means that the server does not store any client session information between requests. Every individual request sent by a client must contain all the information necessary for the server to understand and process it. This design ensures that each request is processed independently, improving scalability and reliability across web servers.