Mastering the Art of Writing API Documentation

4 min readAug 24, 2023


Photo by Sinziana Susa on Unsplash

Documentation’s one of those things that you might think is a nice to have, which couldn’t be further from the truth. It’s like Test Driven Development (TDD), if you’re not doing it as you go it can be an overwhelmingly involved task to complete after the fact.

There’s not a software we build any more that doesn’t ship with an Application Programming Interface (API). Even if we’re consuming it exclusively for our own purposes, it can quickly become rendered ineffective without clear and comprehensive documentation.

Inside of Ascend, we’re now stipulating that API documentation is not a luxury; it’s a necessity. For developers, this can help better understand their work and for project managers, they can understand how something can be implemented or integrated.

With all that in mind, we thought it an idea to explore some words of advice for writing API documentation that enhances stakeholder experience and accelerates development.

Understand the audiences 👩‍👩‍👦‍👦

Before diving into documenting an API, it’s crucial to identify the target audience. Who are we writing this for? The answer will tailor the language in the documentation to suit the audience’s knowledge level.

Provide clear “Getting Started” instructions 🎬

A “Getting Started” section is someone’s first interaction to an API. The “Getting Started” section can be used to give the first step-by-step instructions on how to start working with your API.

You may also choose to loosely document the end-to-end process for clarity of what can/should/could/will be achieved.

Offer thorough endpoint descriptions 📕

There’s nothing worse than bad documentation. It’s almost more frustrating than no documentation at all.

Each endpoint in an API should be documented with precision and detail. As a minimum, including the URL, HTTP method, parameters (query, path, and headers) and a request & response example.

A comprehensive explanation of each parameter’s purpose, data type, requirement and possible values is essential for developers to craft accurate requests.

Consistent structure ⚒️

Documentation should be organised in a clear and consistent manner. Grouping related endpoints together and using a standardised structure for descriptions is helpful in reducing the learning curve.

This consistency makes it easier for readers to navigate and locate information quickly.

Provide real-world examples 🌍

Nothing clarifies concepts like real-world examples.

Include diverse use cases that showcase how to accomplish specific tasks using the API. These examples should cover common scenarios and demonstrate best practices.

Explain error codes and responses ⛔️

Errors are inevitable in API interactions. It’s part of the reason why APIs exist to communicate errors back so they can be fixed.

Clearly document potential error codes, along with descriptive explanations of each. It is an idea to also offer troubleshooting suggestions and to highlight common mistakes that could be encountered.

Detail authentication and security 🔏

Security is paramount in API usage.

Explain the various authentication methods the API supports, such as API keys, Headers, OAuth tokens or JavaScript Web Tokens (JWTs). Providing guidance on how to keep sensitive data secure during transmissions is always a useful reminder to include too.

Don’t let it become a graveyard 🪦

As an API evolves, so should the documentation.

Outdated documentation is worse than little documentation, which as we said is worse than no documentation at all. Regularly reviewing and updating content to reflect the latest changes, additions, and deprecations is something that has to be done.

Include interactive examples 🤝

One of the most effective ways to engage developers is by providing interactive examples. Tools like Postman Collections allow users to make API requests directly from the documentation, enabling them to experiment and understand the API’s functionality in real-time.

Code samples in various programming languages can be immensely helpful to guide developers through their first interactions. Postman Documentation makes this incredibly easy.

Why we use Postman Collections & Documentation

Postman is a popular API development and testing platform. It offers an excellent feature known as Collections. A Postman Collection is a curated set of API requests that can be organised, shared, and easily documented.

Collections provide several advantages when integrated into API documentation:


With Postman Collections embedded in documentation, readers can execute API requests without leaving the page. This hands-on experience enhances understanding and reduces the learning curve without the need for downloads or installed software.

Ease of testing

Developers can use the download the entire Postman Collection to test API endpoints directly from their computer, allowing them to test-run scenarios and troubleshoot potential issues.


By using Postman Collections, it ensures that the provided examples are accurate. Keeping them up-to-date is effortless, since any changes made to the Collection can be reflected in the documentation instantly.


Postman Collections can be easily shared among team members, promoting collaboration and enabling developers to work together on an API without having to dive into code to figure things out.

Wrapping up

Mastering the art of writing exceptional API documentation requires a blend of technical accuracy, user-centered design and clear communication.

By following our tips and leveraging tools like Postman Collections, stakeholders are provided with the resources they need to seamlessly integrate and utilise an API, ultimately enhancing their experience and driving the success of a project.




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