NashTech Insights

Popular Types of APIs

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In today’s interconnected digital world, Application Programming Interfaces (APIs) play an important role in enabling seamless communication and integration between different software systems. APIs serve as building blocks that allow applications to interact and share data with each other, opening up a multitude of possibilities for developers. In this blog post, we will explore some of the most commonly used API types, and discuss their advantages and disadvantages.

Let’s dive into the world of APIs and discover the various types!


RESTful (Representational State Transfer) APIs are one of the most popular types of APIs used in modern web development. They adhere to the principles of simplicity, scalability, and statelessness. RESTful APIs use standard HTTP methods such as GET, POST, PUT, PATCH DELETE, etc., to perform CRUD (Create, Read, Update, Delete) operations on resources, represented as URLs.


  • Simple and easy to understand, making it developer-friendly.
  • Platform-independent, allowing communication between different systems.
  • Scalable and suitable for building large-scale applications.
  • Utilizes standard HTTP methods, making it cacheable and optimized for performance.


  • Real-time communication can be challenging with RESTful APIs since they are stateless and require clients to repeatedly check for updates.
  • Over-fetching or under-fetching of data can impact performance.

When to use:

  • When building web applications or public APIs that follow a resource-based approach.
  • When you require a stateless and scalable architecture for distributed systems.

Example: Let’s consider a simple RESTful API for managing a list of books:

GET /api/books       // Get all books
POST /api/books      // Add a new book
GET /api/books/{id}  // Get a specific book by ID
PUT /api/books/{id}  // Update a book by ID
DELETE /api/books/{id}  // Delete a book by ID

GraphQL APIs

GraphQL APIs have gained popularity due to their flexibility in allowing clients to specify the exact data they need. Unlike RESTful APIs, where clients receive fixed data structures from predefined endpoints, GraphQL APIs allow clients to request customized data and receive it in a single response.


  • Empowers clients to request precisely the data they need, reducing over-fetching and optimizing performance.
  • Supports real-time updates with subscriptions, enabling real-time communication.
  • Enables API versioning without impacting existing clients.


  • Requires additional complexity for backend implementation compared to traditional RESTful APIs.
  • This may lead to increased query complexity if not properly designed.

When to use:

  • When building applications with complex data requirements, allowing clients to fetch only the data they need.
  • When real-time updates and subscriptions are essential for your application.

Example: GraphQL API for getting all books and their authors

query {
  books {
    author {


SOAP APIs are a type of protocol-based API that rely on XML messages to communicate between systems. These APIs define strict message formats and use HTTP, SMTP, or TCP for communication. Because they typically involve complex XML structures, they require well-defined contracts (WSDL – Web Services Description Language) for client-server communication.


  • Well-structured and formalized, ensuring consistency and predictability.
  • Built-in error handling and security features.
  • Suitable for enterprise-level applications requiring strong standards and protocols.


  • Heavier and more verbose compared to RESTful APIs, leading to higher bandwidth consumption.
  • Requires additional processing for parsing and handling XML messages.

When to use:

  • When building enterprise-level applications that demand strong standards and security.
  • When you need built-in error handling and a formalized contract for communication.

Example: A simple SOAP API request to get the weather of a city might look like:

<soapenv:Envelope xmlns:soapenv="" xmlns:web="">


WebSocket is a type of communication protocol that enables immediate and two-way communication between a client, usually a web browser, and a server. This is done through a single long-lasting connection, as opposed to traditional HTTP requests which require the client to initiate communication and are stateless. WebSocket allows both the client and server to send messages at any time, making bidirectional communication possible.


  • Real-time and low-latency communication, making it ideal for applications requiring instant updates.
  • Reduced overhead compared to traditional polling methods for real-time data transmission.
  • Simplified server-side handling due to the persistent connection.


  • Requires support from both the client and server, limiting legacy system integration.
  • It may result in increased server resource consumption for maintaining long-lived connections.

When to use:

  • When you need real-time, bidirectional communication between a client and server.
  • When building applications such as chat applications, collaborative tools, or real-time monitoring systems.


Webhooks are a way to send information from one application or service to another application’s URL or HTTP endpoint automatically. When an event happens, the source application activates a webhook to send details about the event to the destination application. Essentially, webhooks allow for real-time communication and data sharing between applications, making it easier for them to interact with one another.


  • Efficient and event-driven communication, reducing the need for constant polling.
  • Allows for easy integration with third-party services, as it enables real-time updates.


  • Requires the client to have a public endpoint to receive Webhook notifications.
  • The client needs to handle Webhook requests and ensure data consistency.

When to use:

  • When you need to provide real-time updates or notifications to other applications.
  • When integrating with external services that support Webhook notifications.


gRPC is an open-source framework developed by Google, used to build efficient RPC (Remote Procedure Call) services between applications. It utilizes Protobuf as the data format and HTTP/2 for transmitting information between clients and servers. gRPC supports multiple programming languages and streaming, enabling the construction of flexible and high-performance distributed applications.


  • High performance, with support for both synchronous and asynchronous communication.
  • Efficient serialization using Protocol Buffers, resulting in smaller payload sizes.
  • Cross-platform and cross-language compatibility, allowing seamless integration across different systems.


  • Requires a higher level of technical understanding due to its complexity compared to traditional RESTful APIs.
  • It may not be suitable for simple or small-scale applications.

When to use:

  • When building microservices-based applications that require high performance and efficient communication.
  • When you need cross-platform and cross-language support in a distributed system.



Throughout this comprehensive guide, we have delved into six popular types of APIs that offer distinct capabilities to meet various communication and integration needs in modern web development. APIs continue to play a vital role in facilitating smooth interactions between different software systems as technology advances.

  • RESTful APIs provide a simple and scalable approach, making them perfect for building web applications and public APIs. They are easy to comprehend and platform-independent, allowing for communication between different systems. However, they may not support real-time communication and can lead to inefficient data transfers due to over-fetching or under-fetching.
  • GraphQL APIs offer flexibility by allowing clients to request specific data, optimizing performance, and minimizing unnecessary data transfer. They support real-time updates through subscriptions, providing a powerful mechanism for real-time communication. However, their implementation complexity may be a consideration for developers.
  • SOAP APIs are structured and formalized, making them suitable for enterprise-level applications with strict standards and security requirements. They come with built-in error handling and security features. However, their verbosity and higher overhead compared to RESTful APIs may be a trade-off to consider.
  • WebSocket enables real-time, bidirectional communication, making it ideal for applications requiring instant updates and real-time interactions. However, WebSocket requires support from both client and server, which may limit integration with legacy systems.
  • Webhook offers efficient event-driven communication, reducing the need for constant polling and enabling real-time notifications. It allows for easy integration with third-party services and secure data transfer. However, the client needs to handle incoming Webhook requests and have public endpoints, which may require additional consideration for security.
  • gRPC excels in high-performance communication for microservices-based applications. Its efficient use of Protocol Buffers results in smaller payload sizes and supports cross-platform and cross-language communication. However, compared to traditional RESTful APIs, gRPC’s complexity may require additional expertise.

When selecting an API type for your project, consider your application’s specific requirements and performance needs. Each API type has its advantages and trade-offs, allowing developers to create powerful, scalable, and efficient applications tailored to their use cases.

Understanding and leveraging the strengths of these popular API types can enable developers to build robust and responsive applications that meet the modern demands of seamless communication and integration.



Anh Tran is Technical Lead at NashTech. With several years of experience in software development, I have had the opportunity to participate in and contribute to complex technology projects. With a cheerful attitude and a passion for learning, I always seek opportunities to explore new things in the technology industry. I believe that staying updated and applying emerging trends will bring maximum value and effectiveness to projects.

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