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Home / Viewpoint / REST API vs. RESTful API: What's the Difference?

REST API vs. RESTful API: What's the Difference?

The world of web development is brimming with terms and acronyms that often lead to confusion, especially when they sound similar. In this context, 'REST API' and 'RESTful API' are frequently used interchangeably, yet they harbor subtle differences that are crucial for developers and businesses to understand. Let’s embark on a detailed exploration to distinguish between these two terms and shed light on their nuances.

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What is REST API?

REST, an acronym for Representational State Transfer, is a set of principles that guide the development of APIs (Application Programming Interfaces). APIs are the backbone of communication between different software applications, especially over the Internet. Imagine you’re using a weather app on your phone. When you request the latest weather update, the app uses an API to fetch this information from a remote server. If this API is built following REST principles, it’s referred to as a REST API.

Principles of REST APIs

  • Client-Server Architecture: This separation allows for a more scalable and modular development.
  • Statelessness: Each request from the client to the server must contain all the information needed to understand and process the request.
  • Cacheability: Responses should be defined as cacheable or non-cacheable to improve client-side performance.
  • Layered System: The client cannot ordinarily tell whether it is connected directly to the end server or to an intermediary along the way.

What is RESTful API?

While a REST API is based on REST principles, a RESTful API adheres strictly and entirely to these principles. It’s not just about following the guidelines but embodying the philosophy of REST. In a RESTful API, there’s a strong emphasis on simplicity and statelessness, ensuring that each request from the client contains all necessary information independently, without relying on the stored context on the server.

Characteristics of RESTful APIs

  • Uniform Interface: This ensures a standardized way of communicating between client and server.
  • Statelessness: There is no session data stored on the server; each request is standalone.
  • Cacheable Responses: Efficient caching mechanisms improve scalability and performance.

Basic Differences between REST vs RESTful API

At the most basic level, the difference between a REST and a RESTful API lies in the degree of adherence to REST principles. While REST APIs use these principles as a guideline, RESTful APIs follow them to the letter.

Key Differences between REST vs RESTful API

REST API vs RESTful API: Comparison Table

Adherence to REST Principles Follows REST principles as guidelines Strictly adheres to REST principles
Uniform Interface May vary in implementation Consistently maintains a standard interface
Statelessness Generally stateless, but not strictly enforced Rigorously implements statelessness
Cacheability Treats caching as optional Considers caching integral to architecture
Architecture May opt for simpler architectures Prefers rigorous, multi-layered architecture
Stability and Predictability Relatively flexible, varying stability More stable and predictable
Remote Procedure Call (RPC) May incorporate RPC style Avoids RPC, sticking to resource-based approach
Use Case Suitable for less strict REST implementations Ideal for systems requiring strict REST compliance

REST vs RESTful: Architecture

While both REST and RESTful APIs use the client-server architecture, RESTful APIs apply a more rigorous architectural approach, ensuring the separation of concerns and enhancing scalability.

REST vs RESTful: Cache Ability

RESTful APIs consider cacheability as a core feature, using it to significantly boost the performance and scalability of web services. In contrast, REST APIs might treat caching as an optional feature.

REST vs RESTful: Stability

RESTful APIs, due to their strict adherence to REST principles, offer a more stable and predictable environment for developers. REST APIs, with their more flexible interpretation of REST principles, may not always guarantee the same level of stability.

REST vs RESTful: Multi-Layered Architecture

A RESTful API is more likely to implement a multi-layered system, enhancing security and scalability. This is less of a compulsion for REST APIs, which might opt for simpler architectures.

REST vs RESTful: Undeviating Interface

The uniform interface of RESTful APIs ensures that interactions are consistent and predictable, a feature that may vary in REST APIs depending on their design and implementation.

REST vs RESTful: Remote Procedure Call on Web Services

RESTful APIs generally avoid using RPC (Remote Procedure Call) style interactions, sticking instead to a resource-based approach. REST APIs, however, might incorporate RPC, leading to a hybrid style that doesn’t strictly adhere to REST principles.

Why Apidog Is the Best API Development Tool?

Apidog In Api Development
Apidog In Api Development

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Interactive Design & Modeling: Easy-to-use interface for defining endpoints and methods, with a visual editor for API structure.

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Versatility & Integration: Supports various API types and integrates seamlessly into existing development workflows.

Real-Time Feedback: Offers immediate response simulation for quick adjustments.


The distinction between REST and RESTful APIs is crucial in the world of web development. REST APIs, guided by the principles of Representational State Transfer, provide a flexible approach to building web services, allowing for some leeway in how these principles are applied. In contrast, RESTful APIs adhere strictly to REST principles, ensuring a high degree of uniformity, predictability, and scalability. This strict adherence influences various aspects, including architecture, stability, and interface consistency. While REST APIs offer more flexibility and may incorporate diverse approaches like RPC, RESTful APIs prioritize a more standardized, resource-based approach. The choice between using a REST or RESTful API depends on the specific needs of a project, with each approach offering unique advantages in different scenarios.

What is a REST API?

A REST API is a web service that follows the principles of Representational State Transfer (REST) to a certain extent, facilitating communication between software applications over the Internet.

What defines a RESTful API?

A RESTful API is a type of REST API that strictly adheres to all REST principles, including client-server architecture, statelessness, and a uniform interface.

How does the architecture differ in REST and RESTful APIs?

While both use client-server architecture, RESTful APIs apply a more rigorous approach, often implementing a multi-layered system for enhanced scalability and security, unlike the more flexible architecture of REST APIs.

What is the significance of cacheability in RESTful APIs?

Cacheability is a core feature in RESTful APIs, used to boost performance and scalability. In REST APIs, caching might be treated as optional.

Can REST APIs use Remote Procedure Call (RPC) styles?

Yes, REST APIs may incorporate RPC styles, leading to a hybrid approach, whereas RESTful APIs typically avoid RPC, sticking to a resource-based approach.

Which is more predictable, a REST or RESTful API?

RESTful APIs, due to their strict adherence to REST principles, offer a more stable and predictable environment compared to the more flexible REST APIs.

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