What Are APIs and What Are The Different Types of APIs

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API, or application programming interface, is a set of protocols, functions, routines, and/or commands used by programmers to develop software or smooth the interaction between distinct systems.

API defines the interactions between multiple software intermediaries. It has revolutionized the tech world since it defines the requests that can be made and how to make them, as well as the data formats that should be used, conventions to follow, and so on. 

To ensure effective API performance, you need to estimate the optimal type of API in the architecture design. Because APIs are at the core of the programming concept, every programmer should learn how to be highly proficient in it. They must understand the different API types and which will work best for a project according to the intended use case, access to the APIs, and the connected systems and datasets. 

Different types Of API

There are 4 main types of APIs by availability: 

  • Open APIs:  Publicly available with minimal restriction. These may be completely open or require registration or use of an API Key. Open APIs focus on external users, to access services or data.
  • Partner APIs:  Not available publicly but exposed to strategic business partners – usually to a public API developer portal that can be accessed by developers in self-service mode. 
  • Private APIs: Hidden from external users, these are only exposed by internal systems and are not meant for use outside of the company.
  • Composite APIs: These combine multiple data or service APIs and allow developers to access multiple endpoints in one call. Very useful in microservices when you need information from several services to perform a single task.

Different types of API Protocol/Specifications

API protocol specifications are used to standardize the data that is exchanged between web services. This means that diverse systems, running on different operating systems or written in different programming languages are being able to seamlessly communicate with each other.

  • REST API: Representational State Transfer stands for the production of enterprise-grade web applications. It provides the ability to reuse components without affecting the whole process which results in faster performance, ease of use, and reliability. Optimized for web apps, with easy to follow guidelines and minimum bandwidth requirements. 
  • SOAP API: Service Object Access Protocol maintains communication between request and response messages that are sent by web apps. Eventually, every web app needs a SOAP API so that the data is securely transmitted. These have strict rules that need to be followed by developers and are suitable for CRM solutions, payment getaway apps, telecommunication services, and identity management. 
  • RPC API: Remote Procedural Calls are the simplest form of APIs and specify the interaction between the client and the server. These are great for adding procedures and commands and a good option for making CRUD to your app data (create, read, update, delete).

Different types of API by use cases

According to the system for which APIs are designed, they can be: 

  • Database APIs: These enable the communication between an app and a database management system. 
  • Operating systems APIs: These define how apps will use the resources of operating systems. 
  • Remote APIs: These define standards of interaction for apps that are running on different machines.
  • Web APIs: The most common API class which provides machine-readable data and functionality transfer between web-based systems.

In conclusion, knowledge about APIs is very useful when working on web app development projects. It is important to choose the right API that best fits your business model and app development needs.