What is API documentation?

API documentation contains crucial guidelines that explain how to use an API effectively. It’s a reference for other developers to understand how an API should function or be integrated. API documentation must be well-written and include essential information, such as endpoints, parameters, getting-started steps, status codes, and much more. Most importantly, it should be straightforward and precise.

What is the significance of API documentation?

It aids the consuming developer in better understanding the API. It can be an excellent guide to help the developer understand what does what and what’s required.

Better upkeep and versioning

API documentation also allows developers to track what has changed and how the change affects the overall system. They can also refer to previous documentation if they’re using an older version of the API. Good documentation cuts down the time spent onboarding new users.

API documentation tools

API documentation tools help automate and manage the API documentation process. These tools help to present APIs to other developers in a straightforward manner. They’re time-saving, and it’s easy to get started with them. A few of these tools are:

  1. Swaggerhub

  2. Postman

  3. Redocly

  4. Readme

  5. Stoplight

Let’s look at Postman as an example.

Postman

Postman is the best for real-time collaboration. It’s an easy tool used to make machine-readable and interactive documentation. It automatically pulls sample requests, headers, code snippets, and more to populate documentation pages. Its commenting feature allows teams to review and make changes in real-time.

Steps for writing good API documentation

API documentation should include all the necessary details about an API and be well-written. Good documentation makes it simple for internal and external developers to fully understand the API consumption process, rather than contacting the API developers whenever something is unclear. Here are a few steps for writing clear and effective documentation.

Know the users

The first step in creating API documentation is researching our target audience. Are these users already familiar with the product? Do they comprehend how APIs work? We need to answer these critical questions before we proceed. For example, when developing an external API, we must provide as much information as possible about how to use the API, because the developers using it don’t have the luxury of contacting us every time they have a question. As a result, when we write documentation, we must ensure that it’s clear enough for any user group (developers, CTOs, and product managers) to understand.

Elements of documentation

Each API documentation is unique. They do, however, share a few characteristics. Below are the fundamental elements that comprise our API documentation structure.

Note: Please keep in mind that the screenshots in this lesson are just examples. These are just a few samples from the Stripe API documentation.

The introduction section

This section tells the developer what the API is all about. Is it SOAP or REST? How do we handle requests? How do we respond to responses?

API reference page
API reference page

The authentication section

This section discusses the authentication and authorization methods put in place to ensure security. Some APIs demand that users obtain an API key. Developers need these API keys to access the API endpoints. These keys come in pairs (live and test keys). In the production environment, we use live keys, while in the development environment, we use test keys.

Authentication section
Authentication section

The status codes section

This is an important section. It describes the different error codes that a developer may encounter while using an API. When a developer runs into a problem, proper documentation of what each status code means will help them figure out what to do.

Status codes
Status codes

Versioning

Developers use this section to track and obtain important information about the major changes made to an API over time. Developers can find information about the changes to different functionalities and how to port from the previous version to the new version.

Versioning
Versioning

Examples are important

Examples help the consuming developer better understand the API, e.g., how requests should be handled and sent, as well as what to expect as responses. In summary, examples make the whole consumption process easier and quicker to begin.

Example code
Example code

A well-documented project makes development easier and faster. When writing technical documentation, it’s critical to keep our documentation as simple as possible.