APIs can be classified as public or private depending on who can access them and how they are used. Understanding the distinction helps you decide which type of API is best for your business goals and technical needs.

Public APIs

A public API (also known as an open API) is available for use by anyone outside the company. These APIs are designed to encourage third-party developers to build new applications, services, or integrations that enhance the original platform.

Example:

Suppose a company operates an online travel booking platform. It creates a public API that allows external developers to access flight schedules, hotel availability, and pricing information. Third-party travel apps can use this public API to offer their users the ability to search for flights and hotels powered by the company's data. This approach helps the company reach more customers and grow its ecosystem.

Private APIs

A private API is intended for internal use only. It is used by the company’s own developers to connect internal systems, automate workflows, or create new features. Private APIs are not accessible to anyone outside the organization.

Example:

The same travel booking company might also develop a private API that connects its booking engine to its internal customer relationship management (CRM) system. This private API enables the company’s support team to automatically retrieve booking details and customer preferences during support calls. Because this API exposes sensitive internal data, it is kept private and secured.

By choosing between public and private APIs, you control who can access your data and services, and how they are used to support your business objectives.