What Are the Different Types of APIs?

An application programming interface (API) is a set of guidelines for how to communicate with an application. APIs are used in different industries, but are especially important in development. An API effectively acts as a translator between two systems, making it possible for them to interact and exchange information smoothly. Different types of APIs have been developed over time to help businesses extend the functionality of their websites and software.

Read more: How Do APIs Work?

Types of APIs

Public APIs

Public APIs, also known as open APIs, are APIs that are published for general use. With a public API, anyone can request data from any number of companies that use it. Open APIs are a critical component for mobile apps, as well as providing easy integration to major services for many websites. An example of public API that’s been widely adopted would be Google’s Maps APIs.

Private APIs

A private, or closed, API is typically used by a software vendor within its own infrastructure. Internal APIs are often proprietary; they are only used within an organization’s private network. Most organizations use internal APIs to exchange data with various internal business applications, such as customer relationship management (CRM), enterprise resource planning (ERP), or financial systems.

Partner APIs

When two different companies want to share data, they might do so through a partner API. Companies give vendors access to data streams via an API in exchange for added features or services within their own systems. This model allows businesses and developers to connect with another business in a way that wouldn’t otherwise be possible.

Read more: How to Use an API: Best Practices for Beginners

Types of API Architectures and Protocols

REST API

The REST (Representational State Transfer) architecture is an approach to communications that favors a relatively simple interface between components (clients and servers). It emphasizes a limited number of well-defined operations, each with a standard set of formats for arguments.

A critical aspect of this type of access mechanism is its statelessness, in which each request contains all of the information necessary to accomplish its task. Because the calls are stateless, REST is useful for CRUD-type operations, or creating, reading, updating, and deleting data. CRUD functions are often used in web-based REST APIs, where they map to the HTTP methods GET, POST, DELETE, PUT, and PATCH.

REST API Use Cases

  • Web use: REST APIs are typically designed to be consumed by browsers, meaning they provide web users with a new way to interact with websites. They are often used for stateless, cacheable, and discoverable web services.
  • Cloud provisioning: One challenge cloud providers face is accurately tracking infrastructure resources, so clients can pay for only what they use. Many accomplish this using REST APIs in an effort to simplify billing and resource management processes.
  • Cloud applications: REST APIs are used in cloud apps because they are stateless and available across all platforms. Furthermore, since their access mechanisms change from browser-based actions (like form submissions or clicks on buttons to GET/POST requests and response data structured as JSON objects or XML documents), they require server-side components to process them.
  • Enterprise apps: Many developers build enterprise-specific apps based on public APIs — and some companies even publish their own internal services as public REST APIs in order to encourage third-party integrations, opening up possibilities for collaboration between teams or departments.

SOAP API

A SOAP (Simple Object Access Protocol) API is a method for communication between different systems through an XML document. These documents are generally used in web services and help two systems communicate with each other, passing data back and forth over a network connection.

The most popular language for creating these files is XML (eXtensible Markup Language). SOAP APIs are rule-based and strict — they define how your application should interact with external systems. In particular, they are strict with handling rules, commands, and validations.

SOAP API Use Case

SOAP is better suited for enterprises that require a highly customized approach to information sharing. Because it gives you complete control over how you exchange data with other parties, there are fewer security risks than with other methods of communication. However, because of their complexity, SOAP APIs aren’t as user-friendly as RESTful APIs.

RPC API

RPC, or remote procedure call, is a method of communication between two computers in which a service running on one machine requests data from another. This is a type of API that lets you call on any remote procedure and get results from it.

In other words, you can use RPC to make client calls or server calls, depending upon your requirement. This can happen between applications on your computer or across an internet connection between servers. Either way, RPC allows you to access and utilize code stored remotely.

RPC API Use Cases

  • Simplified client/server programming
  • Load balancing with added scalability on demand
  • Flexible applications that can run in a variety of environments and across networks
  • Being able to make configuration changes without having to distribute new clients, thereby making development faster, easier, and less costly

GraphQL API

GraphQL is a query language for APIs and a runtime for fulfilling those queries with your existing data. It provides a complete and understandable description of the data in your API. Further, it gives clients the power to ask for exactly what they need (and nothing more), makes it easier to evolve APIs over time, and enables powerful developer tools.

GraphQL API Use Cases

  • Flexibility and scalability: Traditional APIs have a single-point-of-failure model, which means that one outage can take down an entire business or application. With a highly scalable GraphQL back end, you can get lightning-fast response times with even thousands of concurrent users.
  • Improved data integration: By decoupling data from its back end through GraphQL, developers can focus on creating great user experiences — rather than worrying about messy integrations.
  • Multi-platform support: With GraphQL, it’s possible to write queries once and then run them everywhere.

Top 5 API Platforms

CA API Management

CA API management helps you link systems, modify services, orchestrate data, and establish enterprise-grade APIs from many sources. It also streamlines API development, reducing time-to-market. Developers may cooperate on the platform and utilize the built-in mobile software development kits (SDKs).

Azure API Management

Azure API Management is a cloud-based API administration solution with serverless API management, automatic scalability, and fast provisioning. The platform may be used to publish APIs to external and internal clients, as well as to manage microservices as APIs. Users may choose from a variety of specific use models.

Akana API Management

API security, administration, and publication are all handled by the Akana platform’s end-to-end management solutions. Akana promotes digital outreach, promotes partner endorsement, and manages analytics to enhance data translation.

Tyk API Management

Tyk is an open-source API management platform including an API dashboard, developer dashboard, and API gateway.

AWS API Gateway

Amazon’s API Gateway allows developers to build, publish, monitor, and secure APIs. The gateway allows you to monetize APIs on the Amazon Marketplace.

Choosing the Right API Vendor for Your Business

A wide variety of platforms are accessible once you begin the process of choosing the right tools. As similar as two tools’ principles are, the platforms’ focus might be very different. Security and full life cycle management may be the strong suits of certain types of APIs, while developer engagement and analytics may be the strong suits of others.

When adopting an API integration solution, many factors must be evaluated — including pricing, support models, and vendor reputation. Another essential consideration is how well the solution will integrate into your overall enterprise architecture.

Read next: What Is API Integration?

Aminu Abdullahi
Aminu Abdullahi
Aminu Abdullahi is an award-winning public speaker and a passionate writer. He writes to edutain (Educate + Entertain) his reader about Business, Technology, Growth, and everything in between. He is the coauthor of the e-book, The Ultimate Creativity Playbook. Aminu loves to inspire greatness in the people around him through his actions and inactions.

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