Is API and REST API the same thing?

Is API and REST API the same thing? 80% of web APIs follow REST

The question is api and rest api the same thing arises from RESTs dominance in web services. While they are related, they are not identical. Understanding this distinction is essential for effective API design and communication. Explore how REST principles shape modern web APIs and what sets them apart.

Is API and REST API the same thing? Here’s the clear answer

This question can be understood in more than one way because API and REST API are closely related but not identical concepts. No, an API and a REST API are not the same thing. An Application Programming Interface (API) is a broad term for any interface that allows software components to communicate, while a REST API is a specific type of API that follows the Representational State Transfer architectural style.

In simple terms: all REST APIs are APIs, but not all APIs are REST APIs. Think of API as the category, and REST API as one particular approach within that category. That distinction matters more than most beginners realize.

What is an API (Application Programming Interface)?

An Application Programming Interface (API) is a defined set of rules that allows two software systems to communicate and exchange data. It does not specify how communication must be structured at an architectural level - it simply defines how requests and responses should be formatted and handled.

APIs can exist in many forms: operating system APIs, library APIs, and web APIs. Some use HTTP, others rely on protocols like SOAP, GraphQL, gRPC, or even raw TCP sockets. I remember the first time I built an internal API between two microservices - I thought API automatically meant REST. It didn’t. We were just exposing structured endpoints over HTTP with custom rules. That was my wake-up call.

Let’s be honest: the word API is often used loosely. Developers sometimes say API when they actually mean REST API. That shortcut causes confusion - especially for beginners trying to understand the api vs rest api explained in clear terms.

What is a REST API and how is REST API different from API?

A REST API is a web API that follows the REST architectural style. REST - short for Representational State Transfer - defines constraints such as stateless communication, a uniform interface, and resource-based URLs typically accessed via standard HTTP methods like GET, POST, PUT, and DELETE.

Unlike the broad concept of an API, REST imposes specific design principles. Because REST is stateless, each request must contain all necessary information; the server does not store session data between calls, which significantly simplifies horizontal scaling.

Here’s something counterintuitive: REST is not a protocol like HTTP. It’s an architectural style. Many developers - myself included early in my career - assumed REST was just another protocol specification. It took me a few messy deployments to understand that REST is about structure and constraints, not transport mechanics.

API vs REST API explained through practical differences

When comparing API vs REST API, the difference lies in scope and constraints. API is the umbrella term. REST API is one standardized way of implementing an API over HTTP following specific design rules. This is essentially the core of the difference between api and rest api.

The real confusion often comes from web development culture. Over the past decade, REST became the dominant architectural style for public web services. By 2023, surveys showed that over 80% of publicly documented web APIs follow REST principles in some form, which explains why many people equate API with REST API.^[1] Popularity shaped perception.

But REST is not the only option. GraphQL allows clients to request exactly the data fields they need. gRPC uses a binary protocol optimized for performance. SOAP relies on strict XML messaging rules. Each is an API approach - just not REST.

Are all APIs REST APIs?

No, not all APIs are REST APIs. An API can be RESTful, but it can also follow SOAP standards, use GraphQL query language, or implement gRPC with Protocol Buffers. The term API describes the interface. REST describes the architectural style behind that interface, which answers the question are all apis rest apis.

I’ve never seen a more common beginner misconception than this one. Developers build a simple HTTP endpoint and label it REST without applying stateless constraints or proper resource modeling. That’s not automatically RESTful. It’s just HTTP-based communication, even if someone casually asks is api and rest api the same thing.

This is a common scenario in fast-paced development environments where speed often takes precedence over architectural purity, resulting in APIs that are functional but not strictly RESTful.

REST API vs Other API Styles

REST API

- Moderate - requires understanding resource modeling and HTTP semantics

- Follows REST constraints including statelessness and uniform resource identifiers

- Public web services and CRUD-based applications

- Commonly uses JSON over HTTP

GraphQL

- Steeper due to schema design and query language

- Query-based API allowing clients to request specific fields

- Complex front-end applications with varying data needs

- Typically JSON responses defined by schema

gRPC

- Advanced - involves code generation and streaming concepts

- Uses remote procedure calls with Protocol Buffers

- Internal microservice communication requiring low latency

- Binary serialization for high performance

Case Study: Resolving API Architectural Confusion

Alex, a backend developer at a tech startup, built what he initially called a REST API for a mobile application. While the system functioned correctly for users, he assumed that any HTTP-based interface was automatically RESTful.

A month later, scaling problems appeared. Sessions were stored server-side, and endpoints mixed verbs like /getUserData and /createUserAccount. The architecture felt messy. Debugging at 1 AM with tired eyes and cold coffee, frustration hit hard.

After reviewing REST constraints carefully, he redesigned endpoints around resources like /users and removed server-side session storage. Stateless requests felt strange at first, but the structure became cleaner.

Within weeks, deployment became smoother and scaling horizontally was easier. Alex realized he had built an API before, but only now understood what made it truly RESTful.