What is a REST API? Learn how REST APIs work, their benefits, and real-world examples to help you integrate them into your workflow.
REST APIs power many of the digital services we use daily — in fact, whether you realize it or not, you’re probably using one right now.
Whenever you stream music, track a package, or sign into a website with a social media account, REST APIs – or representational state transfer application programming interfaces – make it happen. They allow web applications to send and receive information in a structured way so that software programs can connect and exchange the data they need to function.
In this guide, we’ll explain what a REST API is, how it works, the benefits it offers.
What Is an API?
An API (application programming interface) is a set of standardized rules that developers use to build and integrate application software. APIs allow different systems to communicate when performing an action or retrieving information, like processing a payment, fetching weather data, or verifying a login. Think of anAPI as a mediator — it enables applications to share data while ensuring security, authentication, and control over access.
Many of the apps and websites people use daily rely on REST APIs. Here are three REST interface examples that power millions of interactions every day:
Google Maps API is used by Uber, food delivery services, and travel apps to provide real-time navigation, location tracking, and accurate arrival estimates.
Spotify Web API enables apps to access song, artist, and playlist data while controlling playback. This is how smart speakers, in-car entertainment systems, and fitness apps seamlessly sync with Spotify.
Instagram Basic Display API allows third-party apps — like social media management tools and website builders — to pull profile photos, videos, and account details to schedule posts, embed Instagram content, and analyze engagement.
From navigation to entertainment and social media, REST APIs make the experience smoother and more user-friendly.
How Do RESTful APIs Work? RESTful Definition
RESTful APIs function via a request-and-response system: When a user sends a request — like submitting a login form or searching for a product in an online store — the API breaks down the request into smaller modules. Each module handles a specific part of the request, such as verifying authentication, retrieving data, or formatting the response.
Then, the API sends back a response, typically in JSON or XML format, that contains the requested data or a status message indicating the outcome (e.g., success, error, or unauthorized access). JSON, in particular, is widely used because its simple structure is easy for humans to read and developers to work with. The lightweight design also uses less bandwidth and loads faster, which helps prevent errors when systems share data.
To send and receive information, RESTful APIs follow standard HTTP methods:
"GET" retrieves data from a resource.
"POST" creates a new resource.
"PUT" updates an existing resource.
"DELETE" removes a resource.
What Is Stateless Architecture?
Unlike traditional web applications that use session-based authentication or shopping carts that remember items between visits, RESTful APIs treat each request independently. This is known as a stateless architecture, meaning the server doesn’t remember past requests.
Instead, every request has to include all necessary details, such as authentication credentials, resource identifiers, and request parameters, for the server to process and respond correctly. Because RESTful API methods don’t rely on stored session data, they can handle a higher volume of requests than other systems and work across a broader range of applications.
3 Uses of REST APIs
REST APIs are widely used in different types of applications because they keep the client and server separate. This means developers can change the front end (what users see) without affecting the back end (where data is stored and processed) and vice versa.
Here are three common REST API use cases:
1. Cloud-Based Applications
Many cloud-based applications use RESTful APIs because they don’t store user data between requests and are easy to scale and update. Some common uses include:
Third-party integrations: Many SaaS platforms, like customer relationship management (CRM) or accounting software, use REST API integrations to connect with email services, payment processors, and other business tools. This allows companies to automate repetitive tasks, such as syncing contacts, processing invoices, or generating reports, without manual input.
Data storage and management:Apps also often use REST APIs to store and retrieve data from cloud services like AWS, Google Drive, or Dropbox. For example, a photo-sharing app might use an API to upload images to the cloud so that users can access them from any device without storing them locally.
2. Cloud Computing
Traditional IT management requires regular manual server maintenance. But in cloud computing, developers use APIs to create, monitor, and adjust cloud resources instead. With less hardware and upkeep, costs are lower.
Resource provisioning: APIs allow cloud platforms to automatically set up virtual machines, databases, and containers based on demand. For example, if a company needs more storage or processing power, an API can create a new database or virtual server without manual setup.
Monitoring and analytics: APIs collect system logs, track CPU and memory usage, and detect performance issues in real time. Developers can identify problems early.
Automation and scaling: To keep up with demand, APIs increase or reduce cloud resources based on traffic. If a website receives a surge in visitors, API servers are deployed, and when traffic slows, excess capacity is removed to prevent overuse.
Cost optimization:APIs can automatically shut down idle servers during low-demand periods, reducing power consumption and, in turn, operational costs.
3. Microservices
In microservices architecture, applications operate as a collection of small, independent components that work together. For example, a food delivery app might have separate services for handling orders, payments, and driver tracking. Each service runs independently but communicates with the others to complete a delivery. Thanks to REST APIs, these services remain separate while still functioning as a unified system. This means updating the payment system, for instance, won’t disrupt order processing or driver tracking.
Typical microservices uses include:
Service decoupling: Each microservice has its own REST API, allowing teams to develop, update, and scale different parts of an application separately. For example, an online store might have one service for handling user logins, another for processing orders, and another for managing inventory. If the store needs to update the login system, it won’t affect how orders are processed or how inventory is tracked.
API gateways: Services like AWS API Gateway help manage how different microservices communicate. They act like traffic controllers, making sure requests go to the right services and enforcing security rules like limiting how many requests a system can handle at once.
Data aggregation: APIs can gather and combine data from multiple restful web services to make information easier to access. Instead of separately requesting a user’s profile and order history, a single API request can pull all that information at once, making applications faster and more efficient.
3 Key Benefits of REST API Services
REST APIs are widely used because they offer significant advantages to both businesses and developers. Here are three key benefits:
1. Increased Scalability
Because REST APIs are stateless, they don’t store client data on servers. This means they use less memory than other systems. They also rely on lightweight HTTP protocols, which makes scaling easier — businesses can simply add more servers when traffic increases.
2. Programming Language Independence
REST APIs follow standard HTTP protocols and use common data formats like XML and JSON, making them compatible with almost any programming language, including Python and JavaScript. This allows businesses to integrate older systems with modern microservices without a full rebuild. It also simplifies connecting with external services like payment gateways.
3. Added Flexibility
Because RESTful API architecture is modular and adaptable, developers can add new features without disrupting the system and customize API responses for different platforms, like mobile and desktop. REST APIs also support third-party integrations, expand services and collaborate with external developers.
5 Design Principles of REST APIs
REST APIs follow a set of rules that make them efficient, scalable, and easy to use. These rules help developers design APIs that work smoothly across different systems. Here are the five main principles of REST API:
1. Uniform Interface
A uniform interface means that all interactions between clients (like web apps) and servers follow the same standards. This makes it easier for different systems to work together. REST APIs follow these rules:
Use of HTTP methods (GET, POST, PUT, DELETE) to perform actions
Self-descriptive messages that provide clear information so the client knows what the response means without extra instructions
Resource identification in requests so that every piece of data has a clear and unique location
Links to related resources (called HATEOAS), which help clients navigate the API without needing extra knowledge
2. Client-Server Separation
REST APIs follow a client-server architecture, meaning that the client (like a website or mobile app) and the server (where data is stored) are kept separate.
The client is responsible for the user interface and making requests.
The server processes requests, manages data, and ensures security.
Since they work independently, developers can update one without affecting the other. This makes applications more flexible and easier to scale.
3. Statelessness
Because REST API is stateless, the server doesn’t remember past requests. Each request contains all the information the server needs to process it.
The server doesn’t store session data. Instead, the client handles it.
Every request is independent, making the API more reliable and able to handle more users at once.
Since there’s no session data stored on the server, REST APIs are fast, efficient, and easy to scale.
4. Layered System
A layered system means that a request may pass through several layers (like security checks or load balancers) before reaching the server.
These layers improve security, reliability, and performance.
The client only interacts with the top layer without knowing what’s happening behind the scenes.
The server can forward requests to other servers, allowing complex systems to work smoothly.
This design makes REST APIs more flexible and scalable, as new layers can be added without changing how the client interacts with the API.
5. Cacheability
To improve speed and efficiency, REST APIs support caching, which means storing data temporarily so it can be accessed faster.
API responses include caching rules, telling clients whether the data can be stored and for how long.
Caching reduces the number of requests sent to the server, improving performance.
By using caching, REST APIs can load data faster and reduce strain on the system, making apps and websites run more smoothly.
The Best of REST APIs — Now for Your EDI
Traditional EDI systems are slow, rigid, and costly to maintain. REST APIs modernize EDI, replacing outdated infrastructure with real-time data exchange, automated workflows, and direct connectivity with trading partners and ERP systems.
With cloud-based EDI, you get the best of both worlds: modern, API-driven integration with the reliability and support needed to keep operations running smoothly. Gain access to real-time message streaming, API management, and change data capture in a single platform.
No more legacy roadblocks or costly delays — just fast, flexible, and scalable EDI. Connect with an EDI expert to learn more about how a cloud-based REST API service can transform your approach to EDI.
