Top REST API Interview Questions (2024)

1. What is REST API?

2. Could you provide some examples of REST APIs?

3. What is Web API?

4. What are the REST Architectural Constraints?

5. What is Uniform interface Constraint in REST API?

6. What is REST API Client-server Constraint?

7. What is Stateless in REST API Constraint?

8. What is Cacheable Constraint in REST API?

Q: What is REST API?
Ans:

A REST (REpresentational State Transfer) API (Application Programming Interface), also referred as a RESTful API is a type of application programming interface (API or web API) that adheres to the REST architectural style's limitations and allows interaction with RESTful web services. It uses HTTP requests to GET, PUT, POST and DELETE data.

Q: Could you provide some examples of REST APIs?
Ans:

1. REST API allows developers to query or search for data and receive results in JSON format.
2. REST APIs give a mechanism to create, update, retrieve, and delete data from a repository database, similar to how Twitter, GitHub, and other applications provide Rest Api to communicate with backend.

Q: What is Web API?
Ans:

As the name implies, a web API is an API that can be accessed via the web using the HTTP protocol. It is a framework for creating and developing HTTP-based RESTFUL services. Different technologies, such as Java and ASP.NET, can be used to create a web API. Web API can be accessed via a web server or a web browser. Web API is essentially a web development idea.

Q: What are the REST Architectural Constraints?
Ans:

REST specifies six architectural constraints that must be met by every web service in order for it to be considered a genuinely RESTful API.

1. Uniform interface
2. Client-server
3. Stateless
4. Cacheable
5. Layered system
6. Code on demand (optional)

Q: What is Uniform interface Constraint in REST API?
Ans:

The uniform interface constraint specifies how clients and servers interact. It improves and decouples the design, allowing each component to evolve independently.

The uniform interface's 4 basic principles are as follows:

1. Resource identification: Every resource should have a unique and consistent URI in order to be made available:

   HTTP/1.1 GET http://techgeeknext.com/get/employees
   

2. Representation of Resource: It is the way via which the resource will be returned to the client. This representation can consist of HTML, XML, JSON, TXT, and other formats.

   {
   "id": 1,
   "name": "AAA",
   "role": "Admin"
   }
   

3. Self-descriptive Messages: Every message has sufficient information to specify how to process the message. So basic information is required in every request and response.

   GET /#!/employee/techgeekgeek HTTP/1.1
   User-Agent: Chrome/95.0.4638.69
   Accept: application/json
   Host: techgeekgeek.com

4. Hypermedia as the Engine of Application State (HATEOAS): Clients receive the state from services via body content, response codes, and response headers. When discussing REST, this aspect is frequently disregarded. It returns all essential information in response to the client's knowledge of how to browse and access all application resources.

Q: What is REST API Client-server Constraint?
Ans:

This constraint effectively says that client and server apps MUST be able to develop independently without relying on each other. A client should only be aware of resource URIs.

Q: What is Cacheable Constraint in REST API?
Ans:

Since clients usually request the same server and frequently request the same resources, it is essential that these responses be cached in order to minimise extra processing and considerably increase performance.