What are the types of APIs and their differences?

An API is an effective and flexible way to connect disparate software programs. APIs enable a wide range of software products that are not related to interoperate and integrate with each other and data. Developers can also add features and functionality using APIs from other developers. A wide variety of APIs is essential for today’s enterprise, mobile, and web software.

APIs may not be the same. Developers have the option to work with a variety of API types, protocols, and architectures that best suit different businesses and applications.

There are four types of web APIs

APIs can be used in web applications and are widely accepted. There are four types of APIs that are commonly used in web services. They can be public, private, mixed, and partner. The API “type” is used to indicate the intended use.

• Public APIs.

Any outside developer can access the API. A public API is available to any business that has a business strategy that includes sharing data and applications with other businesses. These APIs are also known as open APIs and external APIs.

Most public APIs require authorization and moderate authentication. A per-call fee may be imposed by an enterprise to make the API more profitable.

• Partner APIs.

This API is only available to a select group of API users or developers outside the company. It facilitates business-to-business interactions. A partner API allows a business to connect its internal customer data system with external CRM firms. No other API uses are allowed.

Access to such APIs is granted to partners with clear rights and licenses. Partner APIs are generally more secure and have a stronger authorization, authorization, and security features. These APIs are not usually monetized directly by enterprises; instead, partners get paid for their services and not API usage.

• Internal APIs.

A private or internal API is one of the types of API that is only intended for use within an enterprise to connect data and systems within that organization. An internal API could connect an organization’s HR and payroll systems.

Because internal APIs are meant for internal use, security and authentication are typically weak or absent. However, this is changing as organizations become more aware of the threat and comply with regulatory requirements.

• Composite APIs.

Composite APIs combine multiple APIs to create a series of interdependent or related operations. Composite APIs are useful for complex or closely related API behavior and can often improve performance and speed over individual APIs.

Also, read: 10 Best API Testing Tools to Use in 2023 — (SOAP and REST Tools)

Architectures and API protocols

APIs exchange commands or data. This requires clear protocols and architectures. These are the rules, structures, and constraints that regulate an API’s operation. There are currently three types of API architectures or protocols: REST (RPC), and SOAP (SOAP). These could be called “formats”, each with its characteristics and tradeoffs, and used for different purposes.

1. REST

The representational state-transfer (REST) architecture has been the most widely used approach to building APIs. REST uses a client/server model which separates the front and back ends of the API. This allows for considerable flexibility in development as well as implementation. REST is non-stateless. This means that the API does not store any status or data between requests. REST supports caching which stores responses for slow APIs. REST APIs are often called RESTful. They can also communicate with or operate through intermediate systems like API gateways, load balancers, and other APIs.

2. Remote procedural call

This protocol allows you to send multiple parameters and get results. RPC APIs execute executable actions or processes. REST APIs exchange data or resources like documents. RPC can use JSON or XML for coding. These APIs are referred to as JSON–RPC, and XML–RPC.

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