Ever wondered how various applications communicate with each other? It’s through APIs. API documentation plays a crucial role in bridging communication between applications, ensuring smooth integrations and clear functionality. Previously, we discussed the top 5 best practices on technical writing.

In this blog, we’ll explore the essentials of API documentation, focusing on best practices to create efficient, user-friendly guides for developers.

First, let me give you a brief about APIs, the types of APIs, and why API documentation is important.

To begin with, let’s look at what APIs are.

What are APIs?

API stands for Application Programming Interface and API definition is that it is a set of rules which different applications use to communicate with each other and the user interfaces. Applications are responsible for taking information from the various user interfaces (UIs), performing calculations and transactions on the database layer, and then presenting the results back to the user interface.

However, in addition to this, applications must be able to communicate directly with each other. For example, your mobile ride sharing application will need to communicate with the mapping service, the traffic and weather services and other specialized applications used by the drivers providing the rides.

In the modern, interconnected world, all these different systems can interact with each other seamlessly using APIs.

Now that you are conversant with what APIs are, here are the types of API documentation.

Types of API documentation

Stated below are the various types of API documentation:

Fig 1: Types of API documentation

Now, let’s turn our focus to the reasons why API documentation matters.

Why is API documentation important?

It is certainly difficult to develop the API without knowing which endpoint to use and how, nearly none too poor supporting documentation makes it even more difficult to even fix a bug because the source is unknown. Therefore, having well-crafted API documentation is essential for the following reasons:

• Precise documentation helps developers understand how to use the API effectively.
• It makes interacting with the API easier.
• With the help of clear instructions, bugs and errors are reduced.
• Standardized documents help developers in scaling the API with other systems.
• Providing clear guidelines on how to use the API safely will eliminate unauthorized access and data breaches.
• Good documentation also supports compliance with security standards, making it easier to audit and maintain a secure API environment.

Here are the best practices that you can follow while preparing the API document:

Fig 2: API documentation best practices checklist

1. Make It Easy to Read & Search

The document hierarchy describes the structure of the documents that your application is designed to process. Your document must firstly contain the list of all the available APIs in production followed by the methods supported by the API and their workings such as –

Fig 3: Employee API

Once the document structure has been simplified, it would be easier to search for anything across it.

2. Test Before You Write

When looking at an API testing tool, it is important to understand which API technologies you will be using and the best way to test them. Nowadays most APIs you come across will be of the Web Service variety (either REST or SOAP), but you may come across other technologies such as Java EJBs or Microsoft DCOM/ActiveX DLLs as well.

Java, Node.js and .NET are modern technologies that help a business stay ahead in the game.

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So before writing, understand how it works by getting in touch with your team members and ensure that you have the right knowledge which will make it simpler for you to present it to your viewers.

Check for API testing tools within your project and get hands-on on it. This way you make sure that the document is true to its content and learn new concepts and explore your perspectives.

Here are some basic questions that you should be able to answer:

• Which endpoints are available?
• What HTTP verbs can be used with those endpoints?
• Are any of the verbs limited by authorization?
• Which parameters are required in the requests?
• What are the validation limits on the parameters?
• What response codes should be expected for a successful request?
• What response codes should be expected for an unsuccessful request?
• What sort of error messages will be returned to the body of an unsuccessful request?

3. Release Notifications

Release and pre-release/upcoming notes are for both support and marketing. Keep a separate page/section for them.

Sharing release notes regularly sets the right expectations and keeps the users informed. Keep the release notes brief, mention the release date and version, and provide a hyperlink to the API section where the actual change is made.

Sharing the pre-release notes helps users plan for their next move depending on the release. Keep the pre-release brief with UAT screenshot and expected release date(optional).

4. Give Code Examples

Developers strongly rely on API reference information and code examples. Providing interactive demos or sample codes of Request body and Response body is a powerful way to improve the learning curve of consuming your API.

For each endpoint they can view the supportable parameters’ format which answers:

• What are the parameters required to run the API?
• What response body should be expected for a successful request?
• What response error message should be expected for an unsuccessful request?
• What changes should be made to the request body to handle the error?

5. Support API with the related UI Process

If UI is for humans who interact with the face of a software, API is for programmers who interact with it behind the scenes to make the software functional. So, for non-technical visitors, it would be a great idea to explain the user interface experience that is related to the API.

For example, for Employee API, describing how to create an employee record from a front-end application will simplify the understanding of the associate API request and response body. Supporting the API execution with user interface steps will motivate the user to keep scrolling through the document.

6. Use Utility to Reduce Time

Despite being practiced by few, this method has a good impact on the documentation cycle. From a broader perspective, API is going to be present in the long run.

So, for a lengthier webpage document, you can also consider automating the documentation format. Now you only have to copy-paste your content in the utility and it will take care of the structure and view of the page. You can also have your utility switch between different code formats automatically with a click.

You can search for such utilities on the internet or get them developed by the right product development company, which will further reduce your documentation time and formatting burden.

Now, let’s look at how generative AI can enhance API documentation.

GenAI for API Documentation

Generative AI can be used for enhancing and optimizing the preparation of API documentation, in the following ways:

1. Automatic Generation of Code Samples: GenAI can create code examples for each API endpoint, showing developers how to implement specific functions or handle responses, saving time and improving clarity.
2. Dynamic Documentation Updates: As the API evolves, GenAI can automatically update documentation to reflect changes in endpoints, parameters, or error codes, ensuring the documentation stays current.
3. Natural Language Summaries: It can generate human-readable summaries and explanations for complex API functions. This can make it easier for developers of all experience levels to understand the purpose and usage of each endpoint.
4. Interactive Troubleshooting and Error Guidance: By analysing common API errors and their resolutions, it can generate troubleshooting guides. This provides users with possible solutions and tips on error-handling within the documentation.
5. Consistent Terminology and Formatting: It can enforce a standardized style across the documentation, ensuring consistent terminology, layout, and structure, which enhances readability and usability.
6. Automated FAQ Generation: By analysing user queries or documentation search data, it can generate FAQs to address common questions. This further reduces support needs and improves self-service options.
7. User-Centric Documentation: It can personalize documentation based on the user’s role, providing tailored explanations and examples for developers, testers, or product managers.
8. Language Translation for Multilingual Support: It can translate API documentation into multiple languages, making it accessible to a global audience and improving inclusivity.
9. Interactive API Explorers and Tutorials: It can create interactive walkthroughs or “how-to” tutorials within the documentation. It thus guides users through API functionalities in real-time with step-by-step examples.
10. Enhanced Search and Query Assistance: With GenAI-driven search capabilities, users can ask questions in natural language and quickly find relevant parts of the documentation. This leads to an improvement in navigation and user experience.

These GenAI capabilities help streamline the documentation process, reduce manual workload, and ensure a more engaging, up-to-date, and accessible resource for developers.

We hope that the above practices will make your journey to writing great API documentation easier and fulfilling.

Contact us if you have any questions about API documentation or visit us at Nitor Infotech if you would like to know more about other services that we have to offer.