API (application programming interface) documentation is the backbone of tech and software development. API providers must deliver clear and consistently updated documentation to keep users informed and help them avoid programming errors.
Now more than ever, companies are interested in offering state-of-the-art documentation as part of their API management strategy. This also includes aspects like API security, monitoring, and analytics. A recent Traceable report forecasts a substantial 34% compound annual growth rate (CAGR) for the API management market.
This guide explores the key insights into creating API documentation. From practical writing tips to user-centric strategies, it aims to give you the knowledge to develop your own API documentation with minimal effort.
API documentation serves as a guidebook detailing the usage of an API and its services. Within this manual, users can find:
Think of API documentation as a pact between two parties. This clarifies how the second party and its software will react upon receiving specific requests from the first party. These requests are commonly known as API calls, guiding developers on the available functionalities and their implementation.
🔚 Effective API documentation outlines endpoints and explains why and when to use them. It goes a step further by providing precise examples catering to users with various levels of knowledge.
Understanding the types of API documentation ensures good communication between developers and those using the APIs. Each type has a unique role, providing information at different stages of development:
Here are some of the benefits of documenting APIs clearly.
Follow this procedure to write comprehensive, user-friendly API documentation.
Knowing your audience helps determine the amount of detail and technical jargon to include in the documentation.
Begin by identifying the main users of your documentation. Consider two main groups:
🪡 Tailor your documentation by recognizing the intended users’ level of expertise. Keep it to the point by focusing on fundamental explanations for newcomers. If you think more experienced developers will be using the documentation, you can delve into advanced concepts.
Different APIs serve various purposes, such as offering traffic updates in navigation apps or music recommendations in streaming apps.
Despite this diversity, every API documentation should cover some fundamental aspects.
If your API requires authentication, you need to offer users clear authentication guidelines.
Consider the following tips when explaining the authentication process.
When APIs employ multiple authentication methods, the documentation must explain each method. For instance, the YouTube Data API gives users several authentication choices by supporting OAuth 2.0 and API keys.
Image source: developers.google.com
Documenting endpoints and methods ensures standardization across API use. It helps save time for both the API developers and the users.
Provide practical instances that show users how to make requests and handle responses. This way, developers can better understand the main functions of each API endpoint. It can also give them a starting point with customizable code.
🪧 These examples become even more helpful as they demonstrate how the API works in real-world situations.
Think of this as giving users a map to navigate through potential roadblocks. This way, users can troubleshoot issues effectively and have glitch-free interactions with your API.
Detailing error handling involves a three-step process:
🛠️ Sharing status and error codes helps developers and testers prepare for updates.
Inform users about any limitations your API may have. Clearly describe factors like rate limits or quotas to clarify the constraints they may face.
For instance, take rate limiting — a technique that prevents the accidental or intentional abuse of an API. Your documentation should clearly articulate rate limits, usually within the terms of use. Facebook Graph API is a good documentation example that explicitly communicates its limits.
Image source: developers.facebook.com
🚧 Your documentation should also explain how these limitations are enforced and reported. This allows users to understand what to expect from the API and adapt its usage accordingly.
Several tools are available for creating API documentation. We’ve highlighted three of the best.
Image source: redocly.github.io/redoc
ReDoc, an open-source documentation tool supporting OAS 2.0 and OAS 3.0, empowers businesses to publish interactive API documentation online.
Image source: theneo.io
Theneo is an API documentation generation tool. It employs AI-generated descriptions and summaries, eliminating the need for manual effort.
Image source: swagger.io
Swagger UI is a tool that is effective in developing interactive API documentation. It simplifies the process for users by transforming OpenAPI Specification (OAS) documents into visually appealing content using HTML, JavaScript, and CSS.
☝️ Keep in mind the following factors when choosing your tool:
The following case studies show how well-structured API documentation can positively impact user experience.
Image source: twilio.com
Twilio‘s API documentation provides access to various documents, each detailing a specific product capability. The documentation incorporates practical tips, tutorials, and use cases accompanied by screenshots.
For instance, on the “SMS” page, users can find subtopics like “Getting Started” and “API Reference.” Each subtopic provides detailed information, including “How to work with your free Twilio account.” Subtopics also contain sample code for various programming languages, as well as a JSON API response.
Image source: developer.vimeo.com
At first glance, Vimeo‘s documentation resembles examples from other APIs, like Google Maps. Each topic page follows a three-column layout:
However, their “Getting Started” guide stands out. It provides step-by-step instructions for setting up a Vimeo SDK (software development kit), generating access tokens, and making initial API calls. It also includes clear explanations of terms like REST (representational state transfer) and best practices for developer tools.
Image source: stripe.com
Stripe‘s API documentation stands out for its comprehensive tutorials, including a new interactive format. This format breaks down tasks — like embedding a Stripe payment form — into easy-to-follow guides. It also provides related code snippets for simple one-click copying. The text aligns perfectly with the nearby code module.
By this point, you likely have a deeper understanding of how to write API documentation. We asked Dmitry Erashkin, our senior back-end developer, to share some tips on how to elevate API documentation to excellence. He brilliantly cited development gurus Brian Foote and Joseph Yoder:
“If you think that good API documentation is expensive, try bad API documentation.”
Follow these practices to make your documentation stand out.
Simplicity is key when writing API documentation.
👨🏻💻 Be mindful of the API documentation generation method. Documentation generation tools excel at code comments. However, they are not as effective as real explanations written by a developer or technical writer.
Users rely on the information in the API documentation to stay in the loop. Your developers must carry out maintenance periodically to guarantee its accuracy.
Image source: developer.twitter.com
Incorporating interactive elements enhances user engagement.
So go beyond the static text. API explorers or sandboxes, for instance, allow users to test endpoints in real time. They can also make learning more dynamic.
Effective API documentation management involves a two-way street for communication. You should not only share information but also invite user feedback.
Your documentation should contain information on user support and legal transparency.
Image source: shopify.com
Think of which extra resources may complement your API documentation.
See if you can include code samples and SDKs for well-known programming languages linked to your documentation.
While the API serves as the link between an application and its backend code, documentation acts as the bridge connecting the API with developers.
Creating great API documentation is no easy task, often involving an ongoing cycle of feedback and revision. Prioritize a user-friendly structure and keep the content updated to ensure your API documentation hits the mark.
Iustina is a curious copywriter with an analytical mind and a demonstrated history in the advertising industry. She likes mixing words with data and is passionate about human behavior. When she's not at her work desk, you'll probably find her enjoying refreshing tea flavors, spilling stories on paper, or binge-watching true-crime documentaries.
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