Application programming interfaces (APIs) are used in web applications, financial institutions, and video games, to name a few. They define how web applications connect and interact, contributing to the success of several businesses that rely on online data transmission.

So what are APIs, and how can you use them?

What Is an API?

API is an acronym for Application Programming Interface.

An API is a set of well-defined standards or rules that enable different computer applications to communicate. APIs define how applications make data requests, the requests that can be made, and data exchange between different software apps.

For instance, when a flight tracker app displays the planes in a specific location, the app receives data from a flight tracking data service using an API.

In terms of accessibility, there are four major types of APIs: public, partner, private, and composite.

Public APIs, as the name suggests, are widely accessible. They are designed to be utilized by third-party applications and external developers. Examples of public APIs are Twitter API and PayPal API. Partner APIs, on the other hand, are made available for only a selected group of organizations or individuals who have established a partnership with the API provider.

Private APIs are utilized within a specific organization and are not exposed to external individuals. Meanwhile, composite APIs combine multiple APIs from different providers into a single interface. Developers use composite APIs to access various services through a single API call, improving efficiency and reducing complexity.

Types of APIs by Design

APIs differ in style and architecture based on the systems they're designed for. Here are the most common classes of API styles.

Web APIs

Web APIs transfer requests from web applications and server responses via Hypertext Transfer Protocol (HTTP) or Hypertext Transfer Protocol Secure (HTTPS), representing a client-server architecture. Most businesses and organizations use web APIs to connect apps and share data. An example of a web API is the Google Maps API, which you can use to display interactive maps on your site.

Database APIs

As the name implies, Database APIs allow database management systems and applications to communicate. This is achieved by writing queries to the database server to access information, alter tables, etc. A popular example is the ORDS database API, which allows you to execute SQL and PL/SQL commands against Oracle databases.

OS APIs

Operating system (OS) APIs provide instructions on how applications can use the resources of operating systems. All operating systems have APIs, like the Windows API.

Remote APIs

Remote APIs specify how applications running on different computers interact with each other. These remote applications are typically connected over an internet network, so many remote APIs are developed based on web standards. For instance, the Twitter API allows developers to access trends, tweets, and profiles.

How Are APIs Used?

Travel booking websites like Skyscanner and Booking.com use web APIs to aggregate customer flight and destination data. You can instantly confirm the availability of a hotel room and the length of your stay in real time by exchanging your requests and data with the hotel.

Businesses like Oracle Eloqua, Salesforce, and Marketo use APIs to integrate applications to boost lead routing. This allows revenue teams to transfer lead data between customer relationship management (CRM) and the marketing platform and for the customer support team to transmit information between the payment processing system and the helpdesk to better control upsells, renewals, etc.

Social media platforms like Facebook use APIs to process communication between remote endpoints and the platform. Even Twitter bots depend on APIs to function. APIs are also used by service and widget APIs like Google Maps and Weather Report services to provide locations or weather reports to users through simple web-based searches.

Additionally, APIs find use in the financial and payment systems, as banks need APIs to link their backend systems with remote users to process deposits, transfers, balance checks, and electronic payments. Brands like PayPal, eBay, and Amazon rely on APIs to process payments.

The shipping and supply-chain industries are not left out. Processing and shipping your orders generate much real-time data when you shop online. APIs are used when you track your parcels, check the delivery status, and see the current location of your orders.

How to Keep Your APIs Secure, Reliable, and Easy to Use

APIs play a vital role in ensuring seamless integration between systems. However, they can be prone to security issues and cyberattacks. Here are five good practices you can employ.

1. Testing and Quality Assurance

Using automated testing frameworks and tools, you can perform high-quality tests and quality assurance procedures on your API. These tools help identify vulnerabilities in your API and protect it from sensitive data exposure, authentication bypass, and improper access controls.

2. Secure Communication

You can secure your API communication using protocols like HTTPS to encrypt the transmitted data. This protects the confidentiality and integrity of the data exchanged by your API clients. It also shields your server from eavesdropping and data tampering attacks.

3. Error Handling and Logging

Handling involves designing mechanisms to identify and manage errors, while logging involves recording vital information about errors and events during API execution. These processes help you perform efficient audit and debugging processes.

4. Authentication and Authorization

This involves using checks and credentials to identify anyone trying to access your API. Some widely adopted API authorization methods include OAuth 2.0 and API keys. These methods ensure only legitimate individuals can interact with your API.

5. Thorough Documentation and Developer Support

Providing comprehensive and up-to-date documentation and developer support for your API makes understanding and integrating your API easier. When using precise authentication methods in documentation, developers can understand how to validate API requests, reducing verification mechanism vulnerabilities.

Additionally, using API endpoints, parameters, and multiple support channels to structure requests prevents security issues like injection attacks and data tampering.

Simplify Your Workflow With APIs

APIs are powerful because they let you securely tap into data and external functionality. With over 24,000 APIs available, you can take advantage of the functionality of an application like Google Translate without typing a single line of code.