How to write API documentation for optimal user success

Creating documentation is essential when working with an application programming interface (API), but writing it is initially daunting. However, all it takes to get started is time, a sound process, and answers to a few basic questions. You identify who your API documentation is for, why they need it, and how you can fulfill those needs. Then, you define and implement a robust process that slowly but surely shapes your documentation into a thorough guide for its users.

Learn how writing and maintaining effective documentation can enhance user success and streamline your company’s internal knowledge management.

What’s API documentation?

An API is a software interface that enables programs to exchange information like traffic and survey data. API documentation is similar to a how-to manual — it serves as a comprehensive guide for programmers forming queries to the API.

Although many APIs use the standardized OpenAPI specification, no two APIs are the same. That’s why you need to maintain documentation so your users can properly interact with an API. If a user queries for data in an unrecognizable format, the API won’t recognize it and will return an empty response.

An API example is the U.S. National Weather Service (NWS), which makes weather data publicly available to everyone for free. Weather apps like Weather.com query the NWS database in real time to provide weather information to their users. To accomplish this, they program their application to query the database in adherence to the NWS API documentation’s standards.

The benefits of documenting APIs

Documentation’s primary function is to describe your API’s features and how to work with them. Without it, no one but you can use your interface.

Beyond this, keeping thorough API documentation also provides the following benefits:

• Rapid onboarding. Proper documentation accelerates onboarding time for new users, whether they’re employees in your organization or third-party developers picking up your API for the first time. Providing a resource about what to expect from your API helps users quickly determine whether your API suits their needs and how.
• Efficient user support. If your documentation is comprehensive, you can direct users to it for quick and clear answers to their questions. You only need to send them a link to the relevant page and let them problem-solve independently.
• Enhanced user journey. The user experience improves when users have a go-to resource where they can learn everything they need to know about your API. Samples show the API in action, tutorials guide them through setup, and all the reference material is there to answer their questions. And great documentation uses cross-links, indexes, and glossaries that provide relevant information, like methods and definitions when and where needed.

Types of APIs and their target audiences

The first thing to identify before writing your API documentation is who you’re writing it for. If your API is strictly for in-house developers, it’ll look very different than an open API meant for a broader audience. Here are some distinct user targets for your API and its documentation.

Internal APIs

Data-sharing APIs, communication channels, and analytics platforms are all common examples of internal APIs. They tend to be exclusively for your organization’s use to distribute information and programs in a dependable, fast channel. Typically, these APIs use an intranet connection to share and exchange data securely.

Partner APIs

Companies develop partner APIs so their clients can interface with their data and programs. Examples include payment processing services like Google Pay and big data firms like Oracle. These companies provide services, databases, and programs that clients can access by calling their API with a voice request. The organizations’ documentation is highly detailed to help specific clients troubleshoot potential error codes.

Open APIs

Open APIs are accessible to anyone with the know-how to use them (the NWS is an excellent example). These services and databases exist for a broad audience, so they may lack strict security and clearance regulations. Open APIs need thorough and straightforward documentation because there’s no telling who will use them.

Things to consider before writing API documentation

Before you commit to writing your own documentation, consider your audience.

If your API is only for your internal development team, your documentation has a narrower scope, so it’s worthwhile to write. But if you’re hosting an open API for a wider audience, you might need to use an API documentation tool to ensure your documentation is thorough and accessible to a wide audience. And partner APIs typically need their documentation written in-house because they often use proprietary authentication methods and expect unique variables from their clients.

Next, assess whether you have the resources to create your documentation. Even if you leverage automation, documenting takes considerable time and effort from at least one developer. You also need to maintain the documentation in the long term, which often requires a dedicated writer.

If you don’t have the time or staffing power to create and maintain your own API documentation, consider alternative solutions. Some services like Stoplight and ReadMe automatically generate, host, and maintain documentation so you can avoid the hassle.

But if your team has the bandwidth to write their own documentation, it’s a worthwhile process that bridges the gap between your development team and their audience. API documentation maintained by the developers themselves is often more accurate, detailed, and useful. As with anything, the closer a writer is to the source material, the better the outcome.

How to write API documentation: 8 steps

Before creating your own documentation, familiarize yourself with typical API structures. Here are a few well-established examples to help you understand how yours might look and feel:

When you’re ready to begin, follow this eight-step plan for guidance.

1. Create an outline

Start by developing a detailed document outline. Consider it the table of contents and include headings you expect to write for each section. Add as much detail as you feel confident covering at this point. Try not to include anything that’s still in flux, like references to error codes or functions that might become deprecated soon.

A typical outline includes the following parts:

• Introduction
• Samples
• Tutorials
• Authentication
• Endpoint definition
• API reference
• Troubleshooting

Pro tip: Use a style guide for your documentation to refer to while writing it. You can make your own or select one from a well-established brand like Google or Apple.

2. Select a platform

Typically, developers opt to keep their documentation on a website that they share internally or externally. This is a great option when striving to impress partners and third-party developers. Consider using Webflow’s tools and resources, which make it easy to craft reliable, impressive websites at any scale.

Pro tip: If you aren’t familiar with HTML or Markdown, don’t fret! Webflow offers visual development solutions to kick-start your site without a single line of markup.

3. Write the introduction

On your chosen platform, write an introduction that addresses the audience and clarifies the documentation’s goals for both this audience and yourself. Make sure to mention use cases for your API, highlight its features, and describe the documentation’s intended use. Remember, your writing doesn’t have to be perfect yet — you’ll return to polish it later.

Pro tip: Often, over explaining concepts makes them less clear to readers. Opt for simple, straightforward explanations that describe what you mean in the fewest possible words.

4. Create samples and tutorials

Next, collect working examples of your API in action. Grab all the code snippets you need to demonstrate precisely how your API functions and how to integrate it. Then, write some tutorials that explain how the samples work.

Pro tip: Use interactive examples that guide the user through writing their own queries, which can help build confidence.

5. Explain authentication and endpoints

Now that you have working samples, consider the details of how your API handles authentication and what endpoints it expects. Provide examples and use plain language. This should be as concise as possible so users can quickly find and understand the necessary answers.

Pro tip: If documenting a partner API, include a table where partners can look up how to write their unique variables like gateways and merchant IDs. This will allow them to copy and paste what they need, reducing the possibility of common syntax errors.

6. Write the reference material

Your API reference material is where you detail the functions, classes, and arguments that make your API work. Keep it simple and searchable, and use anchors that help users easily navigate the content. Your aim is to reduce the time the user spends scrolling the page for a particular section.

Pro tip: Use consistent formatting to make the page easier to scan. For example, if you’re writing in HTML, use the

 element to ensure all your JSON, XML, and Python snippets appear orderly.
7. Troubleshoot
Document all the common issues you expect users to encounter, like syntax errors and query failures. If your API has known issues like incompatibilities or strict rate throttling, also devote a page to those. This section doesn’t need to be extensive yet. When your documentation is live, you’ll undoubtedly receive suggestions on what to add.
Pro tip: Refrain from creating an FAQ page. If a question is common, you should make the answer easy to locate in the documentation. This encourages users to look for answers in the right places.
8. Clean it up
Now that all your pages are in place, clean up sections that need polishing or expanding. Revise every section to add context where needed and remove anything redundant. At this stage, you can add cross-links to help users navigate the document more efficiently, and include helpful hints and notes where appropriate. Imagine you’re reading the content for the first time, and add anything you think would make the experience smoother.
Pro tip: Before you launch your documentation, ask your peers for feedback. Their fresh perspectives will be invaluable to discovering any errors or improvement opportunities.
Finally, you can launch the documentation and introduce it to your audience.
Maintain your API documentation with Webflow
With your documentation live, it’s time to craft a maintenance plan. Maintenance plans differ based on how many users the API has and how quickly it changes. These factors determine how regularly the documentation needs updating and how your team will capture takeaways from common support cases.
You’re in good hands if you host your documentation with Webflow Enterprise. The platform provides powerful features that simplify updating and maintaining your site, like page branching, Quick Stack elements, and reusable components. And the many documentation templates available make pivoting your site design quick and seamless.
If you want a helping hand, Webflow University hosts all the guides and support options you need.