7 Important Elements to Include When Documenting Your APIs

When designing a new API product, one of the most important steps you’ll need to take is to write the API documentation. In the absence of a tangible interface—and since individual API calls take seconds to complete—documentation helps users understand the scope of the API. That includes its purpose, the way it works, and some examples of how it will perform in its intended use cases.

A well-written and comprehensive piece of API documentation can do more for the main product than simply act as its user manual. API docs will guide their main audience—namely, outside developers—to visualize how the product can work for them. If they like what they see, and it’s immediate to them how much value they can derive from the API, they’re likely to adopt it. Think of your API documentation as more than a means to explain your product, but to actively sell it to your target market.

For you to achieve this, you need to include certain core elements in your API docs. Detailed below is a basic formula or rough table of contents that you can use to create engaging, purposeful, and user-friendly API documentation.

An Overview Section

Just like the foreword or preface portion of a book, the overview section of your API documentation is meant to introduce users to your product. This is where you should aim to make a strong first impression about your service and affirm your users’ decision to onboard your API. A good way to start your overview is to list the following things down:

• What purpose the API was built for
• Important attributes about the API, like the toolkits it was built on or the specification it uses
• The unique selling points of your API in concrete situations

Take care not to overload this section, however, as it only needs to convey the main ideas that drive your API.

The Authentication Section

The second important element that you have to include in your API documentation is a section for authentication. Authentication of users’ identity is an essential part of your API’s security, which of course is a quality you want to prove to your users. In this section, you should explain what authentication schemes the API uses. It’s also good practice to detail how to access credentials and how to use the API’s keys for making requests.

A Section with All the API’s Resources

The next important element in your API documentation—and what will probably comprise the “meat” of your docs—is a list of your API’s resources. Resources pertain to all the information that will be returned by your API. You will want to have a complete catalogue of the following in your documentation:

• Your API’s endpoints
• Your API’s parameters (its headers, paths, queries, and request body parameters)
• Request examples for your API
• Corresponding response examples and schemas used by your API

An Error Messages Section

The error messages section is a particularly important element of your API documentation. It’s a given that your users may experience errors while using your API, but they have to know what went wrong. You should have a full list of error messages with corresponding error codes explaining what each error means. Your users would appreciate it very much if you can also inform them on how to fix the error and complete a successful request.

A Section with Use Cases and Examples

The fifth key element in your API documentation is a section with pertinent use cases and examples. This section will illustrate particular situations in which your API works. If you’re writing static API documentation, it’s enough to curate a list of the most common or relevant use cases. But if you’re keeping interactive API documentation, say for example on a hosted toolset, you can even include code “recipes” for users to try themselves.

An FAQ or Tutorial Section

At this point in your API documentation, you’ll likely want to place an FAQ or tutorial section with more in-depth information about your API. Think of the most common questions or concerns that your users may have when they’re calling your API. Account for every “what if” question they may have and forward a possible solution.

A Section About Limitations and Terms of Use

The last section of your API documentation can be dedicated to the “fine print,” or the proper terms of use and the API’s limitations. For transparency’s sake, be upfront to your users about what the API can and can’t do, as well as how your service is best consumed. The clearer you are about issues like usage constraints or rate limits, the more aligned your users’ expectations will be with yours.

Conclusion

Together, the abovementioned elements will form a good working structure for your API documentation. To make the task even easier for you, consider doing your documentation on a dynamic toolset and not simply relying on .DOC or .PDF documents. You may also want to advocate a style guide for your team, so that more than one person knows how to document the API properly. Lastly, be very conscientious about updates and versioning, because your API documentation must be up-to-date for it to be of relevance to your users.

Now that you have a framework for documenting your APIs, as well as tips on how to approach the task, it’s time to get to work.