How Technical Writers Document APIs

Master the methodical approach technical writers use to create effective API documentation, from understanding APIs to publishing and maintaining documentation that developers love.

Table of Contents

API documentation is essential for helping users understand and use APIs effectively. However, writing good API documentation can be a challenging task. This chapter will teach you the best practices for writing API documentation, from understanding your audience to researching the API to testing your documentation.

For Beginners
If you're diving into this chapter and finding some of the technical terms a bit daunting, don't sweat it—that's perfectly fine! We haven't covered them yet, and my main goal in this chapter is to give you a sneak peek into how you'll kickstart your journey in documenting APIs once you become an expert. As we progress through the course, we'll delve deep into the nitty-gritty details of these terms and technologies.

1. Understand the API

Imagine this: You’re handed a mysterious gadget. It’s shiny, looks powerful, but you have no idea what it does. What’s the first thing you’d do? Yep, figure out what it’s for!

APIs are like that gadget—they solve specific problems and serve specific purposes. Your job is to understand what the API does, how it works, and why it’s awesome.

  • Ask Questions! What’s the API’s purpose? What problems does it solve? Who uses it?
  • Get your hands dirty! Test the API yourself, chat with developers, and dive into any existing documentation (even if it’s messy—this is where you shine!).
  • Pro tip: Don’t be afraid to ask “silly” questions. Some of the best documentation starts with, “What the heck does this do?”

2. Know Your Audience

Let’s pause for a moment. You’re not just writing for the sake of writing. You’re creating something that real people—developers, product managers, or analysts—will use. So, let’s figure out who these people are.

  • Developers: They want the details. Endpoints, parameters, authentication—give them all the nuts and bolts.
  • Product Managers: They’re more interested in the big picture. How will this API improve the product? What are the use cases?
  • Business Analysts: They might want a mix—some functionality details, but also how this API solves business problems.

Think of it like planning a speech: Are you talking to a room full of tech wizards or a group of curious business folks? Tailor your tone and content accordingly.

Different audience segments for API documentation
Understanding the diverse audience for your API documentation

3. Set Documentation Goals

Imagine being handed a map with no “X marks the spot.” Frustrating, right? That’s why you need to set clear goals for your documentation.

Ask yourself:

  • What should someone be able to do after reading this?
  • Should they be able to make their first API call? Understand common errors? Master advanced features?

For example:

  • Goal 1: Help users get started with the API in under 10 minutes.
  • Goal 2: Reduce support tickets by clearly documenting error messages.

When you know your goals, the documentation practically writes itself (okay, not quite, but it helps a ton).

4. Gather API Information (The detective work begins)

  • Once you’ve identified your audience and documentation objectives, you can start obtaining API data.

    • To obtain important API information, work with Subject Matter Experts (SMEs) and other stakeholders.
    • Ask relevant questions.

API Purpose and Functionality:

Example Question: 'Could you explain in simple terms what this API is designed to do and why it's important?'

Key Features and Endpoints:

Example Question: 'What are the primary features or functionalities that developers can access through this API?'

Programming Languages and Frameworks:

Example Question: 'Do developers typically use specific programming languages or frameworks when integrating with this API?'

Authentication and Security:

Example Question: 'What authentication methods or security measures are in place to protect the API and user data?'

Rate Limits and Usage Guidelines:

Example Question: 'Are there any rate limits or usage guidelines that developers need to be aware of to prevent abuse of the API?'

Data Formats and Response Types:

Example Question: 'What data formats does the API accept and return (e.g., JSON, XML), and how should developers handle responses?'

5. Plan Your API Documentation Structure

Think of your documentation like a house. You need a solid foundation and clear rooms where everything belongs. Here’s a tried-and-true structure:

  1. Introduction: What’s the API about? Why should users care?
  2. Getting Started: How to sign up, get an API key, and make the first request.
  3. Authentication: Explain the security basics (e.g., API keys, OAuth).
  4. Endpoints and Methods: Break down each endpoint with supported methods (GET, POST, etc.).
  5. Examples and Use Cases: Real-world examples that show users how to achieve their goals.
  6. Error Handling: Common errors and how to fix them.
  7. Best Practices: Tips for using the API effectively.
  8. FAQs: Answer the most common questions.

If that seems like a lot, don’t worry! Start simple, then expand as you go.

Try it yourself: Documentation Structure Builder

  • Introduction

6. Write Clearly and Concisely (Keep it simple)

Good documentation isn’t about sounding smart—it’s about being understood. Here’s how to do that:

  • Use plain language. If you can say something in 10 words instead of 20, do it.
  • Avoid jargon. If you must use technical terms, explain them.
  • Add examples! A single example can clarify what 10 paragraphs of text can’t.
  • Keep your tone consistent. If your introduction is friendly, don’t suddenly turn robotic in the error handling section.

7. Include Code Samples in API Documentation

Want to win the hearts of developers? Give them working code samples. Think of it as giving them a recipe instead of just describing the dish.

  • Include samples in multiple programming languages if possible (e.g., Python, JavaScript, Java).
  • Test the samples yourself to make sure they work.
  • Use comments in the code to explain what’s happening.
Example of code samples in multiple programming languages
Effective code samples in multiple programming languages

8. Test the API Documentation (Become the User)

Here’s a secret: Testing the API yourself isn’t just helpful—it’s essential. By putting yourself in the user’s shoes, you’ll catch errors, clarify steps, and build empathy for their experience.

Testing Tools
Postman: Great for testing and visualizing API requests.
Swagger UI: Handy for interactive API documentation.
cURL: Perfect for command-line testing.
Insomnia: A lightweight, user-friendly API testing tool.

Create a simple test plan and run through every scenario. If something feels confusing to you, it’ll definitely confuse your users.

Make a test plan and run extensive tests to validate the API’s functioning.

9. Review and Gather Documentation Feedback

Writing is only half the battle—getting feedback is where the magic happens.

  • Share your draft with developers, SMEs, or even a small group of external users.
  • Ask questions like:
    • “Does this make sense?”
    • “Are the examples helpful?”
    • “What’s missing?”

Be open to constructive criticism. Every bit of feedback makes your documentation stronger.

10. Publish and Maintain API Documentation

Congrats! You’ve written amazing API documentation. Now, it’s time to share it with the world.

  • Choose a platform to host it (e.g., Swagger, Postman, GitHub Pages).
  • Update it regularly. APIs evolve, and your documentation should, too.
  • Notify users of major changes. A quick email or update log goes a long way.

Keep in mind that proper API documentation is an ongoing process. It should change in tandem with the API and your users’ requirements. Update and improve your documentation on a regular basis to ensure it stays a helpful resource for developers.

API documentation lifecycle showing creation, testing, publishing, and maintenance
The continuous lifecycle of API documentation

Next up: Explore Different Types of APIs that you might document as a technical writer.

Frequently Asked Questions About API Documentation

Get answers to the most commonly asked questions about creating effective API documentation.

API Documentation Basics

Documentation Formats and Standards

Creating Effective Documentation

Documentation Maintenance and Best Practices

Interactive Documentation

Key Takeaways

  • Understanding the API is the essential first step for creating effective documentation
  • Know your audience to tailor the documentation to their needs and technical level
  • Set clear goals for what users should be able to accomplish with your documentation
  • Structure your documentation logically with getting started guides, reference sections, and examples
  • Test everything yourself to ensure accuracy and identify user pain points
  • Use examples and code samples to illustrate key concepts and use cases
  • Regular review and updates keep documentation valuable as the API evolves

Test Your Knowledge

Check your understanding of API documentation processes with this quiz.
Question 1 of
Technical Writing Expert

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Essential API Documentation Resources

Expand your knowledge with these carefully selected API documentation resources.

External Resources

Tools & APIs

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