Application Programming Interface (API)

An API (Application Programming Interface) is a software intermediary that allows different programs or applications to communicate with each other.

What Is an API?

An API (Application Programming Interface) is a set of rules and protocols that allows different software applications to communicate and interact with each other. It defines a set of functions, protocols, and data structures that developers can use to create software applications and ensure smooth communication between them. APIs specify how different software components should interact and exchange information, enabling developers to build applications that leverage the functionality and data of other applications or services. 

Two links representing two programs linked together by an API.


What Are the Functions of APIs?

The functions of APIs can vary depending on their specific implementation and purpose. Here are some common functions of APIs: 

Data Access 

APIs can provide access to data stored in a database or a remote server. This allows developers to retrieve, update, and manipulate data from different sources. 


APIs facilitate the integration of different software applications and systems. They define a standard way for different components to communicate and exchange information, enabling seamless integration and interoperability.  

Functionality Extension 

APIs enable developers to extend the functionality of their application by integrating with other services or platforms. For example, social media APIs allow developers to incorporate features like sharing, posting, or login with social media accounts. 


APIs can automate tasks by providing a programmatic interface to interact with software or hardware devices. For example, APIs for IoT (Internet of Things) devices allow the control and gathering of data from connected devices. 

Developer Ecosystem and Third-Party Integration 

APIs enable developers to build on top of existing platforms or services, fostering a developer ecosystem and promoting third-party integration. This allows for the creation of new applications, services, or plugins that can leverage the existing platform’s functionality. 

Security and Access Control 

APIs can enforce security measures and access controls to protect sensitive data and resources. They can require authentication, encryption, and other security mechanisms to ensure that only authorized users or applications can access the API’s functionality. 


What Are the Types of APIs by Accessibility?

Private APIs 

Private APIs are intended for internal use within an organization. They are only accessible to authorized users or systems within the organization. These APIs are often used to integrate and communicate between different internal systems or services.  

Partner APIs 

Partner APIs are used to provide limited access to specific external partners or third-party developers. These APIs allow collaboration and integration with trusted partners, enabling them to access and interact with certain functionalities or data of an organization’s platform or service. 

Public APIs 

Public APIs are open for access by any external developer or organization. These APIs are usually provided as a means to extend the functionality of a platform or service to a larger audience. They have clear documentation and are made available to the public for integration and development of third-party applications. 

Open APIs 

Open APIs are a subset of public APIs that embrace the principles of openness and transparency. They are accessible to any external developer or organization without restrictions or mandatory requirements. Open APIs encourage innovation, collaboration, and the creation of an ecosystem around a platform or service.  


What Are the Types of APIs by Functionality?

Web APIs 

Web APIs, such as HTTP APIs or REST (Representational State Transfer) APIs, are designed to be accessed over the internet through standard web protocols like HTTP. These APIs enable access and interaction with web-based services or resources, which can include account management, usage tracking, or billing functionalities. 


SOAP (Simple Object Access Protocol) are often used in enterprise environments due to their reliable and secure nature. They require a predefined contract to be established between the service provider and consumer, which includes the structure of the message exchanged and the procedures for processing it. 

Real-time APIs 

Real-time APIs, often used in chat applications or collaborative tools, facilitate instant updates of data between applications and users. These APIs can be used to track and update usage data in real-time or provide real-time notifications to users about their usage. 

Database APIs 

Database APIs allow developers to interact with databases programmatically. These APIs can be used to retrieve customer details, track usage data, or manage billing information. 

Cloud APIs 

Cloud service providers offer APIs to access and interact with their cloud-based services, such as storage, computing resources, machine learning, or data analysis tools. These APIs enable developers to leverage the capabilities of cloud platforms within their applications.  

Payment APIs 

These APIs enable organizations to accept and process payments from customers based on their consumption and provide functionalities for recurring payments, managing subscriptions, and handling billing and invoicing. 

Geolocation APIs 

Geolocation APIs provide access to location-based services, allowing applications to determine a user’s geographical location or retrieve information related to nearby places and points of interest. They can help companies identify where their products and services are most popular and embed location-based services into their applications and services, ranging from ride-sharing and delivery apps to social media and e-commerce platforms. 

Data APIs 

Data APIs provide a standardized way to access, manipulate, and retrieve data from a specific source, such as a database, web service, or application, making it easier for developers to integrate and interact with the data programmatically. 

Machine Learning APIs 

Machine learning APIs provide pre-trained models and algorithms to integrate machine learning capabilities into applications. They can provide insights into customer behavior, optimizing pricing strategies, personalizing the user experience, automating processes, and improving fraud detection. 

Identity and Authentication APIs 

These APIs help secure access to services, ensure proper user authentication, and manage user roles and permissions. 


Internet of Things (IoT) APIs enable connection and interaction with IoT devices and platforms. These APIs facilitate communication between devices, data collection, and integration with applications. They can be used to monitor and control devices remotely, collect sensor data, or create IoT-driven applications. 


It’s important to note that these categories are not exhaustive, and there may be other types of APIs based on specific use cases or industries. 




While both SOAP and REST APIs serve the purpose of connecting applications with server-side data, they differ in terms of complexity, flexibility, and level of standardization. SOAP APIs are more rigid, standardized, and rely on XML for message formatting, while REST APIs are more flexible, lightweight, and use HTTP for communication in multiple data formats. 



  • Relies on XML for message formatting. 
  • Provides a comprehensive set of standards and features. 
  • Leverages protocols like HTTP, SMTP, or TCP for communication. 
  • Supports enterprise-level features such as WS-Security and WS-ReliableMessaging. 
  • Suitable for applications requiring rigid standards and reliable messaging. 



  • Operates over the HTTP protocol. 
  • Supports multiple data formats including XML, JSON, or plain-text. 
  • Uses HTTP verbs (GET, POST, PUT, DELETE) for CRUD operations on resources. 
  • Stateless and does not require additional dependencies or standards. 
  • Preferred for simpler and scalable web services. 


APIs and Usage Data Management

APIs play a crucial role in usage data management. Here are a few key aspects: 

Data Collection and Integration 

APIs enable the collection and integration of data from various sources. They provide a standardized and efficient way to gather data from different systems, databases, or applications. By connecting to APIs, organizations can easily retrieve and consolidate usage data from multiple sources for analysis and decision-making. 

Real-time Monitoring and Analytics 

APIs facilitate real-time monitoring and analysis of usage data. By integrating with APIs, organizations can access and monitor data streams in real-time. This allows them to analyze usage patterns, track performance metrics, and generate insights for optimizing their systems or applications. 

Workflow Management 

APIs enable external systems to control workflows and workflow groups. They can start, stop, enable, or disable these processes, providing greater flexibility in managing operations. 

Data Sharing and Collaboration 

APIs enable secure and controlled data sharing between different systems or organizations. Organizations can expose APIs to share usage data with trusted partners, vendors, or customers. This promotes collaboration, fosters innovation, and allows for the creation of value-added services or applications built on top of the shared data. 

Automation and Efficiency 

APIs streamline data management processes and enhance operational efficiency. By automating data retrieval and processing through APIs, organizations can reduce manual efforts, eliminate redundant tasks, and ensure data integrity. This efficiency enables faster decision-making, improved customer experiences, and cost savings. 


What Are the Emerging Trends in APIs?

Treating APIs as Standalone Products 

APIs are being treated as separate and independent products, with their own development, marketing, and monetization strategies. This approach enables organizations to unlock the value of their APIs and attract external developers. 

Serverless Architecture 

The rise of serverless architecture is influencing API development. APIs are being designed to support serverless functions, allowing developers to build more scalable and event-driven applications. 

API Generation 

Automating the API creation process and ensuring standardization across APIs is an emerging trend. API generation tools are being used to streamline the development process and make it more accessible to a wider range of developers. 


Related Terms

Data Collection 

Data Integration 

System Integration 

People also ask

  • What is an API key?

    An API key is a unique code used to authenticate API requests, track usage, and manage access to specific functionalities or data within a service or platform.

  • What is an example of an API?

    Google Maps API enables developers to integrate map functionalities and location data into their apps or websites.

  • What does API mean for dummies?

    API stands for Application Programming Interface. It's a way for software applications to communicate and share data with each other, like a middleman.

  • What is an API used for?

    APIs are used to enable software applications to interact with each other, access features or data, automate processes, and integrate services.

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