Understanding REST API vs RESTful API: What is the Difference?

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Posted on February 7, 2024

Today, understanding the nuances between different types of APIs is crucial for creating efficient and scalable web applications more than ever before.

Two commonly discussed terms in this realm are REST API and RESTful API.

While they might sound similar to newbies, there are distinct differences that API developers should understand, especially when navigating the REST vs RESTful world.

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Our practical guide of REST vs RESTful differences can help you better understand these two approaches to API design and their application in your projects. In this article, we explore REST API and RESTful API, their main differences, and how to decide which is best for your web application.

Let’s start with definitions of REST API vs RESTful API.

What is REST API?

Simply put, Representational State Transfer (REST) is an architectural style used in designing network apps. This style is based on a stateless, client-server communication protocol known as the golden standard for creating a network application.

On the other hand, the Representational State Transfer Application Programming Interface (REST API) is just an interface based on REST’s principles. Developers adhere to this code of behavior while creating their API.

APIs should be resource-oriented, and resources are identified by Uniform Resource Identifiers (URIs). The REST APIs use various HTTP methods (such as GET, POST, PUT, DELETE, and PATCH) for operations on these resources.

What is RESTful API?

As we already clarified, RESTful API is just an API built with the REST architectural constraints and principles in mind.

Although all RESTful APIs are REST APIs, not every REST API is RESTful.

In an actual RESTful service, each component (client and server) works individually from the other but communicates with one another through interfaces via HTTP requests and responses.

RESTful APIs are based on resources and their representations. These resources should be easily identifiable through a single URL and only be operated using standard HTTP.

RESTful APIs are also designed to be lightweight, maintainable, and scalable, which makes them one of the most common options for web services.

REST vs RESTful APIs: 10 Key Differences

Digging into web services and API design, you can find various discussions on REST API and RESTful API.

It is necessary to understand the subtle details that characterize each and learn how they influence web application design and performance. This knowledge is essential in making architectural decisions or if you need to optimize existing systems.

As we already clarified, the REST vs RESTful debate isn’t just about terminology but the principles, practices, key features, and philosophies underpinning effective web service design.

Here, we’ll explore ten key distinctions that set REST vs RESTful APIs apart. These differences range from their adherence to REST principles to their implementation of statelessness, resource identification, and more.

1. Adherence to REST Principles

Although REST APIs can use some REST principles, they do not follow them in all respects. The result needs to be more consistent in implementation.

In contrast, RESTful APIs are dedicated to applying REST principles, including statelessness, client-server architecture, cacheability, a layered system code on demand, and uniform interfaces.

This close adherence guarantees greater consistency and standardization, making the RESTful APIs more predictable for developers.

2. Statelessness

Statelessness is a core principle of REST. Both REST and RESTful APIs are stateless, meaning the server does not store any state about the client session.

However, RESTful APIs rigorously maintain this principle. Every client request in a RESTful API must include all the data required to interpret and fulfill that request. This freedom from the server’s state increases scalability and reliability.

3. Resource Identification

In RESTful APIs, the approach to resource identification is more consistent and clear. Each resource, whether a document, an image, or a service, has its own Uniform Resource Identifier (URI).

This approach streamlines the API structure and makes it user-friendly because any resource is reached and adjusted via its particular URI. This contrasts with some REST APIs where resource identification might be more complex.

4. Uniform Interface

The uniform interface of RESTful APIs is a notable difference between REST vs. RESTful API, which is more strictly implemented in RESTful APIs. This means that the API’s interface should be uniform across various types of resources.

The uniform interface simplifies and decouples the architecture, allowing each API part (client and server) to evolve independently. This leads to easier maintenance and a more scalable system.

5. Client-Server Independence

The RESTful vs. REST API difference is prominent in their client-server independence. This principle guarantees that the client and server can be developed and evolve independently of each other as long as the interface between them remains constant. Such separation provides better flexibility and scalability since changes made on the server side will not affect the client’s part and vice versa.

6. Layered System

A layered system architecture in RESTful APIs highlights the difference between RESTful web services and REST APIs. This implies that the client does not have to communicate directly with the final server. It may be linked to a proxy server (such as a load balancer or cache), improving security, load distribution, and caching. This architecture provides a more structured and scalable environment, which benefits complex systems.

7. Cacheable Resources

Emphasized more in RESTful APIs, caching significantly differs between RESTful services and REST APIs. RESTful APIs enable better performance, scalability, and user experience by caching resources. The client may store a cacheable resource for future requests, thus eliminating subsequent requests to the server and reducing bandwidth.

8. Demand-driven Data Transfer

An excellent example of REST API vs RESTful API differences is when demand-driven data transfer is implemented using RESTful APIs. This implies that the API can provide only the required information, not a complete data set. This effective mechanism minimizes the data transmitted over the network, making responses faster and saving server load.

9. Code on Demand

This is an optional constraint of REST and is often seen in RESTful APIs. The server can extend the client’s functionality by sending executable code.
This feature helps enhance the client’s functionality without needing pre-installed software, providing a more flexible and dynamic user experience.

10. Standard Methods

All operations in RESTful APIs are made using standard HTTP methods. These methods include GET (for getting a resource), POST (for creating a new resource), PUT (for updating an old resource), DELETE (to delete the resource), and PATCH for partial update of the resources. Standardization of the methods used, therefore, guarantees a uniform client-server interaction.

So, What Is the Main Difference Between REST and RESTful APIs?

The primary difference between REST API and RESTful API is that while the former does not strictly follow the principles of REST, the latter remains loyal to these principles. Though both are REST-based, REST API does not necessarily follow all REST constraints, while RESTful API follows them completely.

The REST architectural style defines a set of constraints and best practices for the design of web services. These principles include statelessness, client-server architecture, cacheability, uniform interface, and layered systems.

When the API is RESTful, it follows all these REST principles with strict compliance. This rigidity guarantees that a RESTful API remains highly performant, scalable, and modifiable.

Although most APIs are designed with the REST principles, not all can be considered genuinely RESTful. For an API to comply with REST, it must enact these principles precisely in its design and implementation. This also involves the explicit use of HTTP methods, preserving statelessness, ensuring that resources are uniquely identified by URIs, and implementing hypermedia as the engine of application state (HATEOAS), just a few practices.

REST vs. RESTful API: What to Choose for Development?

When choosing between a REST API and a RESTful API for web applications, what to choose, REST vs. RESTful, mainly depends on the specific needs and constraints of the project, as both have their advantages and ideal use cases.

Let’s have a look at them:

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This comprehensive guide covers the differences between REST API and RESTful API – two crucial web and API development concepts. This is important for developers and architects to decide on API design and implementation, especially when considering the REST vs RESTful controversy.

REST APIs are built on the foundations of Representational State Transfer but may follow only some of its limitations. Such flexibility might be beneficial in some cases, especially for a smaller project or if you need to integrate with legacy systems. In comparing RESTful API vs REST API, this adaptability is one of the factors that highlights the difference in these APIs.

In contrast, RESTful APIs are dedicated to the principles of REST architectural style and adhere to its statelessness, uniform interface, and client-server independence. This compliance ensures RESTful APIs are more scalable, maintainable, and efficient for large-scale and dynamic web applications. The difference between scalability and maintainability is significant in their comparison.

However, there is no universal answer when choosing between a REST API and a RESTful API: what works best for one project might not be suitable for another. Factors to consider include the size of your application, the need for scalability and performance, and the importance of adhering to REST principles when making this decision. The REST API vs. RESTful web services factor is essential to this decision-making process.

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