API (Application Programming Interface) is a method for two computer programs to communicate with each other.
API documentation is as successful as your API is. If you want third-party developers to understand how your program works, you need to publish API documentation that explains everything in a crystal clear manner.
We have now started to rely on APIs in a digital-first world. Different weather and stock apps you see on your smartphone provide you with real-time data through the use of an API. And it’s not limited to this.
Social media platforms and almost every SaaS-based product that we use come with an API. It is not possible to develop everything for a product. That’s a primary reason for each service to come up with its own API.
And that’s why it is important to create good API documentation.
API documentation, similar to user documentation, is a technical manual that explains how to use and integrate the API and its service. In this interactive documentation, you can see code examples, manuals, and screenshots. This documentation is critical for internal developers and third parties on knowing what and how to use the API.
In simple terms, consider API documentation as an agreement between the API developer, and the third parties using it. It provides details on API calls, which developers can then study to know the services the API provides.
What Are the Types of API Documentation?
There are three types of API docs:
- Public or External – Available for anyone and help to increase your brand awareness
- Private – For use within a company to help employees in integrating new systems
- Partner – Not public, but only for partner firms
Public APIs are free, whereas Private APIs may require a payment for the private key.
What Should API Documentation Include?
When creating API documentation, it is imperative to answer the following questions:
- What does the API do?
- Who can use the API?
- What are the endpoints?
- How to use it for API calls?
- What basic functions does the API perform?
- What is the API’s lifecycle on future updates?
Once you have the answers to these questions, you will have a better idea of who to write the API documentation for
Here is a structure of API docs:
The first section of API’s documentation is the overview. Consider it like an abstract page for your university thesis or project. It contains:
- Summary of the API functionality
- The problem that your API solves
- Links to API reference documentation
- Benefits of using this API over your competitors
The overview section is important because it lists all the important elements of your API and its functionalities.
2. Authentication Methods
When writing API documentation, it is important to mention the different authentication methods that the end user will have to follow.
Authentication is crucial to API’s data safe for developers and end customers alike. It can have more than one instance of the authentication method. You need to mention each one for users to start accessing and consuming the API.
Bitly and Youtube are two excellent examples that illustrate how to generate and obtain API keys for authentication.
3. Rate Limits
Similar to user authentication, limiting rates can stop intentional or accidental abuse of an API. Rate limits define how many times you can send a request to an API within a specific time period.
4. Error Messages
Error messages are critical as they inform your end users when there is something wrong with the integration. Provide all types of errors and give solutions for each. This eliminates the guesswork from the end users and ensures they can remove errors themselves.
Resources are integral components of your API. Provide an explanation to the consumers on how they can use these resources.
This is the legal agreement between your company and the end user, which governs the terms of usage. These include:
- API limits
- Liability of any damages
7. Change Log
Provide complete detail on API updates and latest versions alongside complete details of changes for each version. This will help the end users make any changes before implementing their next API calls.
API Documentation Examples
To illustrate our points, here are some best API documentation examples.
Stripe API Documentation
Stripe is the first name that comes to mind when developers think about API documentation. Because Stripe is a payment gateway, the API documentation lists everything that developers and end users need to integrate the gateway on websites and mobile apps.
The text-based format comes with interactive documentation. It provides details in a step by step process on how to integrate payments, issue refunds, and build checkout pages.
Twilio API Docs
Twilio is another name that demonstrates the proper use of API design. Within the docs, you can find SDKs in multiple languages and sample apps for iOS, Android, and the web.
The API docs come with 3 columns. You can find additional information with screenshots and accompanying material to help integrate Twilio.
Mailchimp API Docs
Mailchimp’s end users are digital marketing professionals. That’s why its API is well written in a simple and easy-to-understand language without any technical jargon. The two-column layout works great with a nice table of contents on the left, and the information on the right.
How to Write API Documentation?
API management tools help you to write and improve your API documentation, which is a time-taking process.
While you can get started with writing documentation using Google Docs or Microsoft Word for free, it is better to invest a small amount into powerful API management tools.
These tools will make your life easy because of the powerful features that they come with. You can use pre-made templates and other collaborative features to write API documentation and save time, instead of starting everything from scratch.
Here are some great tools that you can use to write API documentation.
Postman is a powerful tool for API documentation.
As of April 2022, it has over 20 million registered users and comes with a public library of 75,000 open APIs.
You can sign up for free and download its PC version to try it out. It has great features to share documentation with your internal team.
DapperDox is an open-source tool that has pre-made themes and layouts for creating API docs. You can use a number of features such as diagrams and specifications to give a visual appeal to your docs, making it interesting for the end users.
SwaggerHub is another popular API documentation tool that many technical writers find easy to use.
The personal use is free, but if you have a team working on APIs, then the minimum price plan starts at $90/month for 3 designers and 6 consumers.
What Are the Benefits of API Documentation?
Over the last few years, API documentation is showing signs of strong demand. This is a technical skill that many developers are not capable of. To improve developer experience, API documentation is compulsory, but not in a technical language.
A technical writer can write API documentation breaking it down into several components to make it easy for other developers to understand and implement.
You can write the best code, but without functional interactive docs, your API is of no use. Here are some of the benefits of writing API documentation:
1. Better User Adoption Rates
Great API docs have a direct impact on developer experience, which leads to higher adoption and usage rates. Imagine buying an expensive LED TV, not knowing how to operate it. Worse, it doesn’t come with a user manual to teach you how to use the product. The best API documentation is one that can explain its consumption to API developers and its users.
2. Increased Awareness
API documentation with a detailed developer guide, code snippets, and API description goes a long way in increasing its awareness. When users see value in the documentation, it will people will vouch for your API.
The easier your API documentation is, the higher your adoption rate.
3. Helps in Saving Time and Costs
Whether you’re referring to internal developers or third parties, great API docs reduce the onboarding time, leading to reduced costs.
Good documentation of API saves the hassle of replying to a flood of emails from agitated users. With code samples and technical content, you can continue maintaining your API while writers document it.
Best Practices of API Documentation
Software developers build APIs. Since they know the ins and outs of API development, they know what type of content needs to go into the documentation.
And that’s the main problem.
Developers are not good writers and they will write the API documentation in a complex and technical language, making it difficult for the end user to understand.
The best solution is to assign a technical writer the task of writing API docs. Technical writers are experts in their fields and can write without any complexities. Technical writers have multiple sessions with the API developers to understand how the API works, and then create user tutorials and guides for documenting it.
In this process, API developers guide the technical writer to ensure that the end result represents complete usage of API.
The end result is a win-win situation where developers and writers are not overshadowing each other.
Here are some points to consider when writing API documentation:
1. Write in a Plain and Simple Language
Do not use technical jargon or terms that the end user cannot understand. It is important to know who your target audience is. Do not assume your target audience has technical expertise. Write as if you are writing for a non-techie.
2. Have Excellent Code Examples
Having long blocks of text does no good if there are no example responses to go along with it. If you are writing about a particular API and its usage, demonstrate with code examples. MailChimp, Twitter, Twilio, and Stripe all do an excellent job with code examples in their API documentation.
Code examples and snippets provide pragmatic tips to developers on how to integrate the respective APIs.
3. Regular Updates From Time to Time
What is the point of having API documentation if nobody can find it? Adding to this, when was the last time you updated the documentation? Every time you make a change in your API, you should reflect those in the documentation.
4. Organize Information Using Tags
You can organize relevant code snippets and examples by tagging them. This helps that the documentation stays organized according to the user’s requirements.
There are three main types of documentation users:
5. Have a Getting Started Guide
The Getting Started guide is a quick guide to help your users in using your API within the quickest time possible. The Getting Started guide highlights key features and quick introduction to your API. Braintree has an excellent guide that provides key benefits of integrating their APIs.
6. Provide SDKs and Libraries
SDKs are not easy to build, but if you dedicate extra time and resources, you will have a much better adoption rate of your API than those without one.
SDKs and code libraries go hand-in-hand. Developers can call multiple resources using your libraries. If your SDKs and APIs seem valuable to developers, they will build their own and add to the existing libraries.
This refines developer experience and helps in improving adoption rates.
7. Interactive Console
What is the point of having extensive documentation without providing a technical way to for developers to test your code?
The API console empowers developers to test your API from within the documentation. This is like a sandbox environment with limited liability for damages. Testing and experimentation are critical to ensure your API is working the way you want it to.
The tools and best practices will help you to get started with writing your first API documentation in no time. However, you need to consider your target audience, their technical understanding, and the reason for writing this documentation.
Now that you have a good understanding of what API documentation is and how to write one, it is time to start developing yours. Writing the documentation isn’t rocket science, but as suggested earlier, it is better to hire technical writers for this task.