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What is API, what is it used for? What are the types of API?

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PlusClouds Author

Cloud & SaaS

What is API, what is it used for? What are the types of API?

API term is now defined solely as an Application Programming Interface and we cannot consider ourselves to have found a complete answer to the question of What is API . In its simplest definition, an API ( Application Programming Interface / Application Programming Interface ) is a set of programming codes that enables data transfer between one software product and another, and also defines various types of software and even hardware interfaces.

Privileged points of API-enabled software:

  • No necessity to have an idea about what is happening in the backend.
  • The capacity to seamlessly hold all complexity.
  • Ensures the mechanism structure is as organized and clean as possible by adhering to determined principles.

What are the types of API?


  • Public API / Open API

An open programming code designed for the use of any third-party developer with minimum restrictions is referred to as Public API or  Open API . Access to processes can be made using a registration; API key or  OAuth based on the provider's request, or access can be completely open.


Examples such as the distribution of publicly available information like weather data and stock market information can be given.

  • Private API / Internal API

Designed for use within a company/project, Private API is used only by the relevant internal systems. This feature distinguishes it most clearly from Public API.

Areas of use: It is used by different development teams for processes such as efficient productivity within the company, the reuse of services, and integration across different platforms.

Private API is an example of any company's internal system. In the case of PlusClouds, the same APIs are used to display and process information in places like crm, account, and panel.


  • Partner API

The type of API given to strategic business partners or offered by these partners is called Partner API . These APIs are not publicly available and require special permission for access. More specifically, this type is  not as highly accessible as Public API but is also not as inaccessible as Private API.

An example of a website suitable for the API sharing among integrated firms can be given as a Partner API type.


  • Composite API

The type of API that combines multiple services or data at a single point is called  Composite API, created using the editing capabilities of any API creation tool. Access rights to other APIs in this type are granted through a single API .

Just as in Partner API, Composite API  type can be exemplified by shopping sites. The shipping company's and bank's access rights are only carried out through the API it provides specifically to the relevant shopping site.

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Frequently Asked Questions

What is an API and what is it used for?

An API, or Application Programming Interface, is a set of programming codes that enables data transfer between one software product and another, and defines various interfaces for software and even hardware. It allows different systems to communicate and can expose functionality or data to external developers when a Public API is used.

What are the main types of API described?

The post describes four types: Public API (Open API), Private API, Partner API, and Composite API. Public APIs are designed for third party use with fewer restrictions, Private APIs are for internal use within a company, Partner APIs are shared with strategic partners under restricted access, and Composite APIs combine multiple services or data at a single point.

How can Public Open APIs be accessed and authenticated?

Public APIs can be accessed after registration and using an API key or OAuth, or access can be completely open depending on the provider. This enables third party developers to interact with the API under defined authentication rules.

What is a Private API and what is it used for?

A Private API is designed for use within a company or project and is intended for internal systems only. It supports internal processes, reuse of services, and integration across different platforms.

What is a Partner API and who can access it?

A Partner API is provided to strategic business partners or by those partners. It is not publicly available and requires special permission for access, making it less accessible than Public API but not completely inaccessible.

What is a Composite API and how does it work?

A Composite API combines multiple services or data at a single point and is created using API creation tools. Access rights to other APIs within this type are granted through a single API, and an example is a shopping site that uses a shared API to access shipping and banking services.

What are common examples of data provided by Public APIs?

Examples include weather data and stock market information that are publicly available. These illustrate how Public APIs share data openly to support apps and services.

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