Technology

What is REST API?

A REST API is a web service that lets one program ask another for data over ordinary HTTP, using standard HTTP methods such as GET, POST, PUT and DELETE. The request is a URL, the reply is usually JSON. sthan.io's address APIs are REST APIs: one GET request, one JSON answer, an API key in the header.

Last reviewed: September 29, 2026

Quick Definition

REST API (Representational State Transfer Application Programming Interface) is a web service architecture that uses standard HTTP methods (common examples are GET, POST, PUT and DELETE) to exchange data between systems. REST APIs communicate using JSON or XML formats, enabling applications to integrate seamlessly and share functionality over the internet in a language-agnostic manner.

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Understanding REST API

REST APIs have become the dominant architecture for web services, powering everything from mobile apps to enterprise integrations. When you check weather on your phone, book a ride with Uber, or verify an address at checkout, you're interacting with REST APIs. These APIs provide standardized interfaces for applications to request and exchange data, enabling the interconnected digital ecosystem we rely on daily.

The REST architecture, defined by Roy Fielding in 2000, emphasizes simplicity and scalability through key principles. REST APIs are stateless - each request contains all necessary information, eliminating the need for servers to maintain session data. They use standard HTTP methods with clear semantics. Common examples: GET retrieves data, POST sends data for the server to process (often creating a resource, but also searches and other actions), PUT replaces an existing resource, and DELETE removes it. PATCH, HEAD and OPTIONS are also standard. This consistency makes APIs intuitive to learn and use.

REST APIs organize functionality into resources identified by URLs (endpoints). For example, sthan.io's address verification API uses GET https://api.sthan.io/v2/address-verification/usa/speculative/{address} to verify addresses. Each endpoint processes the request and returns structured JSON responses with HTTP status codes indicating success (200), errors (400, 404, 500), or other states. This predictable structure simplifies integration and troubleshooting.

Modern applications depend heavily on REST APIs for core functionality. E-commerce platforms integrate payment APIs (Stripe, PayPal), shipping APIs (UPS, FedEx), and address verification APIs. Mobile apps consume REST APIs for authentication, data synchronization, and feature delivery. Microservices architectures use REST APIs for inter-service communication. SaaS platforms expose REST APIs so customers can build custom integrations and workflows.

The business value of REST APIs is transformative. APIs enable rapid development by providing ready-made functionality - developers can integrate address verification, payment processing, or mapping in hours instead of months. APIs create new revenue streams through API-as-a-Service business models. They enable ecosystem growth by allowing partners and customers to extend platform capabilities. Companies with strong API strategies report faster time-to-market for new features and reduced development costs through API reuse.

How REST API Communication Works

  1. Client Request: Application sends HTTP request to API endpoint with method (GET/POST), headers (authentication), and body (JSON data)
  2. Authentication: API server validates credentials (API key, OAuth token) to authorize the request
  3. Request Processing: Server parses request data, validates inputs, and executes business logic
  4. Data Operations: Server queries databases, calls other services, or performs computations as needed
  5. Response Formation: Server formats result as JSON, adds HTTP status code and headers
  6. Response Return: Client receives response, parses JSON, and uses data in application logic or UI

Key Benefits of REST APIs

Platform Independence

Work with any programming language, framework, or platform that supports HTTP requests

Scalability

Stateless design enables horizontal scaling and efficient load balancing across servers

Simple Integration

Standard HTTP methods and JSON format make APIs easy to understand and implement

Caching Support

HTTP caching mechanisms improve performance and reduce server load for repeated requests

Flexibility

Multiple data formats (JSON, XML) and versioning support enable evolution without breaking changes

Wide Adoption

Industry standard with extensive tooling, libraries, and developer expertise available

Common Use Cases

1. Mobile Application Backend

Mobile apps consume REST APIs for authentication, data synchronization, push notifications, and accessing server-side functionality

2. Third-Party Integrations

Integrate external services like payment processing (Stripe), shipping (FedEx), address verification (sthan.io) via REST APIs

3. Microservices Communication

Enable inter-service communication in microservices architectures where each service exposes REST endpoints

4. Web Application Data Layer

Single-page applications (React, Vue, Angular) use REST APIs to fetch and update data without page reloads

5. Partner Ecosystem

Expose platform functionality via public REST APIs enabling partners, customers, and developers to build integrations

REST API vs SOAP API

Feature REST API SOAP API
Protocol HTTP/HTTPS HTTP, SMTP, TCP, others
Data Format JSON, XML, HTML, plain text XML only
Architecture Architectural style (flexible) Strict protocol specification
Complexity Simple, lightweight Complex, verbose
Performance Faster, less overhead Slower due to XML processing
Caching HTTP caching supported Not cacheable
Best For Web/mobile apps, public APIs Enterprise, legacy systems
Adoption Dominant for modern applications Declining, used in legacy systems

How to Integrate with sthan.io REST API

sthan.io provides a simple, well-documented REST API for address services. Here's how to integrate:

Step 1: Get API Credentials

Sign up for free at sthan.io and get your API credentials from the dashboard

Try it live

Step 2: Make REST API Request

Request 
GET https://api.sthan.io/v2/address-verification/usa/speculative/1600%20Amphitheatre%20Pkwy%20Mountain%20View%20CA%2094043
Authorization: Bearer YOUR_TOKEN

Step 3: Example Code (JavaScript)

JavaScript 
const address = encodeURIComponent('1600 Amphitheatre Pkwy Mountain View CA 94043');
const response = await fetch(
  `https://api.sthan.io/v2/address-verification/usa/speculative/${address}`, {
  headers: {
    'Authorization': 'Bearer YOUR_TOKEN'
  }
});

const data = await response.json();
console.log(data.fullAddress);

Frequently Asked Questions

REST stands for Representational State Transfer. It's an architectural style for designing networked applications, using stateless communication and standard HTTP methods. REST APIs are widely adopted because they're simple, scalable, and work with any programming language.
Common examples are GET (retrieve data), POST (send data for the server to process, often to create something), PUT (replace existing data), and DELETE (remove data). Other standard methods include PATCH (partial update), HEAD (like GET but returns only the headers) and OPTIONS (ask which methods an endpoint allows). POST is not only for creating: many APIs use it for searches or for any request whose input is too large or too sensitive for a URL.
JSON (JavaScript Object Notation) is lightweight, human-readable, and supported by virtually every programming language. It's more concise than XML, parses faster, and is easier to work with in web applications. Most modern REST APIs use JSON as their primary data format.
REST API security typically uses HTTPS encryption, API keys in headers (Bearer tokens), OAuth 2.0 authentication, and rate limiting. Always use HTTPS to encrypt data in transit, validate inputs, and implement proper authentication and authorization for all endpoints.

Related Terms

Address Verification Geocoding Reverse Geocoding Address Autocomplete Address Parsing Address Standardization

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