Difference Between REST API and RESTful API

Both REST API and RESTful API are often used interchangeably in the software development community, but there are subtle differences between the two. Understanding these differences is important for building modern web applications, as both have significant roles in enabling communication between client and server.

In this article, we will explore the key differences between REST API and RESTful API, their definitions, features, and how to decide which one suits your project requirements.

What is a REST API?

REST API (Representational State Transfer Application Programming Interface) is an architectural style for building web services that enable communication between client and server over HTTP. While a REST API follows many of the principles of REST (such as using standard HTTP methods), it may not necessarily implement all the constraints that define a fully RESTful API.

REST APIs can be flexible in their design, sometimes skipping specific conventions, depending on the system’s requirements. For example, a REST API might not strictly follow statelessness or might not fully use HATEOAS (Hypermedia As The Engine of Application State).

Features of REST API

• Stateless: While it is not mandatory for a REST API to be fully stateless, it generally follows this principle for simplicity and scalability.
• Flexible Data Formats: REST APIs can return data in multiple formats, including XML, JSON, or even HTML, depending on the client’s needs.
• Basic HTTP Methods: REST APIs utilize HTTP methods like GET, POST, PUT, DELETE to perform actions on resources.
• Simpler Design: A REST API is often designed with more flexibility in mind, allowing developers to customize the implementation based on the requirements.

Use Cases of Rest API

• Basic Web Applications: REST APIs are commonly used for communication between a client and server in basic web applications that don’t require to follow strict REST principles.
• Mobile Applications: They are widely used in mobile apps where communication between client-side applications and servers needs to be efficient and easy to integrate.

What is a RESTful API?

RESTful API refers to an API that follows the principles of REST, but it goes a step further to fully implement the constraints of REST architecture. While REST API is a general term for any web service that uses REST principles, RESTful API refers specifically to an implementation that follows all of REST’s design constraints, including the use of HTTP methods, stateless communication, and proper resource identification.

Key RESTful API Principles

1. Statelessness: The server does not store any client state between requests. Each request must contain all the information the server needs to understand and process it.
2. Client-Server Architecture: There is a separation between the client (user interface) and server (data and logic), ensuring that both can evolve independently.
3. Uniform Interface: RESTful APIs use a consistent, standardized approach to interacting with resources using HTTP methods and URLs. This includes standardized naming conventions for resources and actions.
4. Layered System: RESTful APIs can be built with multiple layers, where each layer has a specific role, such as caching or security, without affecting the client-server communication.
5. Cacheability: Responses from the server must be explicitly labeled as cacheable or non-cacheable, promoting high performance in certain cases.
6. HATEOAS: A RESTful API often includes links in its responses to allow clients to navigate the available resources dynamically.

Features of RESTful API

• REST Principles: RESTful APIs strictly follow the six architectural constraints of REST (Stateless, Client-Server, Uniform Interface, Cacheable, Layered System, and Code on Demand).
• Use of HTTP Methods: RESTful APIs consistently use the appropriate HTTP methods to interact with resources (e.g., GET for retrieval, POST for creation, PUT for updates, DELETE for removal).
• Resource Identification via URIs: Each resource is accessible via a unique URI (Uniform Resource Identifier), making it easier to access and manipulate data.
• Separation of Concerns: RESTful APIs promote a clear separation between client and server, allowing them to evolve independently.

Use Cases of RestFul API

• Complex Web Services: RESTful APIs are ideal for systems that need to expose large sets of resources with clear, standardized interactions.
• Microservices: They are widely used in microservices architectures, where each service needs to be independently scalable, maintainable, and discoverable.
• Public APIs: Many public APIs, such as those provided by Google and Twitter, follow RESTful principles to ensure that they are easy to use and integrate with.

Difference Between REST API and RESTful API

Here is a detailed comparison of REST API and RESTful API based on various features

When to Use REST API

• For Simple Projects: If your project has simple data interaction needs and doesn’t require a complex system for handling resources, REST API is a good choice. It offers flexibility and is easy to implement, especially for smaller applications or quick prototypes.
• When Flexibility is Needed: If the application needs to work with varying data structures or doesn’t need to strictly follow REST guidelines, REST API offers the flexibility to design your endpoints and data interactions as per your requirements.

When to Use RESTful API

• For Large-Scale, Complex Applications: If you’re building a large, scalable system with many interconnected parts, such as an e-commerce platform or enterprise system, RESTful API ensures a standardized, reliable, and consistent approach to data handling.
• When Consistency is Important: If the application needs to guarantee strong data consistency, transaction integrity, and a clearly defined structure, RESTful API is the ideal choice because it strictly follows REST principles.
• For Performance and Scalability: If the project requires optimized performance with high scalability, RESTful API is better equipped to handle large volumes of data and high traffic due to its adherence to REST constraints.

Conclusion

While REST API and RESTful API are often used interchangeably, they have distinct differences. REST API is an API that follows the principles of the REST architecture, while RESTful API is an API that follows the principles of the REST architecture and meets specific requirements. Understanding the differences between REST API and RESTful API is essential for choosing the right API for your web application and achieving optimal performance and user experience.