What Is API Documentation?

Companies of all sizes are relying on APIs to ignite their digital transformation or take it to the next level. APIs have the power to unlock new business value by making data and functionality available to an ecosystem of developers and partners.

However, the success of any API program depends on the level of API adoption and actual utilization. To facilitate adoption, it must be easy to find the API. To ensure utilization, its purpose as well as the effort it takes to integrate it in client code should be easy to understand. Hence, the importance of clear and comprehensiveAPI documentation. 

What Is API Documentation?

API documentation is technical content that describes the API in detail. It includes instructions on how to effectively use and integrate the API, with an emphasis on any security constraints. It also provides updates with regard to the API’s lifecycle such as new versions or impending retirement. Some aspects of API documentation, in particular the functional interface, can be generated automatically using Swagger, OAS or similar specifications.

Once an API is published, API documentation makes sure another party (both internally and externally) knows what it can be used for and how it should be used.

Think of API documentation as a reference manual that has all of the information you need to work with the API. It tells the developer/partner/consumer everything that is possible with the API, and how to get started.

Benefits: Why Write API Documentation?

A large reason why API documentation is important is to increase API adoption. Comprehensive documentation on all of the functionality, how to effectively use and integrate, and updates on the API lifecycle improves the experience for those using your APIs.

Could you use an API without documentation? Sure, it’s technically possible. But you can grasp the API’s technical content and integration instructions much better with complete and accurate documentation.

API documentation is important in your lifecycle. But do you know everything there is to know about the lifecycle? Explore our hub and become an expert today. 

👉 Become an Expert. Explore the API Lifecycle Hub >>

The Importance of Having API Documentation In Sync

API Documentation should reflect the actual API implementation at all times. In other words, the documented interface should be in sync with the implementation of the interface. Client code will be created or generated from the documentation; if out-of-sync, a successful invocation of the API is likely to fail.

Prior to promoting an API product to its production environment, it is essential to test its interface. Such testing can be a tedious, even overwhelming exercise, especially with APIs that offer a significant number of operations, contain many different parameters or describe a number of potential responses. In such cases, the use of API testing tools quickly becomes indispensable. Blazemeter by Perforce offers powerful API functional testing capabilities: a comprehensive collection of reusable test cases is generated automatically based on the input API document (Swagger, OAS).

To continuously validate the published interface while updates in the API’s implementation are ongoing, again you can use a tool like Blazemeter to send validation requests at given intervals. The response is registered and automatically compared to the expected response, with alerts being generated when things are off.

Documenting API Security

APIs will often provide access to valuable business functions and confidential data. To ensure these are only accessible by authorized users, API access control and additional API security are of critical importance.

Providing a detailed description of how developers should handle the security constraints associated with the API is another essential aspect of API documentation. Taking documentation one step further would include an interactive test capability, to give developers a much better understanding by allowing them to execute pre-formatted tests against the API’s sandbox endpoint. Seeing generated requests and returned response in detail greatly accelerates understanding of any security policy associated with the API.

API Documentation Example: What Does It Look Like?

API Documentation should at least contain/cover the following elements:

1. API interface documentation, typically in the form of Swagger or OAS. Developers can use this documentation to generate functional client code;
2. Developer guide providing information on use cases that the API is meant to support, and how to implement those use cases. For example, what API operations should be invoked in which order to implement a complete use case?
3. Security guide, providing detailed information on API access constraints and any other applicable API security policies and how to implement these in client code.
4. Potentially, additional documents that describe contractual conditions, usage plans, etc.

Authorized Access to API Documentation

Not all API resources may be available to any user (or to the client app this user intends to build). Conditional access to API resources should be reflected in its documentation. For example, API operations that are only accessible to users with explicit privileges should not even be visible to non-privileged users.

Akana’s built-in authorization model allows for fine-grained access to API operations, with the API documentation only showing the operations a user is permitted to see. 

How to Create API Documentation With Akana

Documenting your API product is easy with Akana. The following short video shows you how to document an API within the Akana API management platform.

For any API product created within Akana, the functional documentation is generated automatically in OAS format. In its development stage, changes can be made to this documentation iteratively. Furthermore, the generated OAS documentation can be enhanced by providing descriptions of operations, parameters and other functional elements.

The API product can be given a concise description and more elaborate summary to give developers an immediate understanding of the main purpose and functionality of the API.

Additional documents can be uploaded to the API product in the form of html or pdf documents. HTML documents appear as an integrated part of the Portal, whereas pdf documents are presented in a pdf viewer with all functionality associated with pdf docs.

A special customized document is the Akana API Recipe. Essentially, this is an html document with embedded test client instances, providing a highly interactive end result. API Recipes are particularly suited to provide use case descriptions, allowing the developer to gain more insight in any API operation by executing requests that take applicable security constraints automatically into consideration.

Akana Makes API Documentation Easy

As we have seen, Akana makes API documentation easy. The Platform automatically generates the functional documentation, which can be further enhanced if needed.

Furthermore, API product owners are able to upload and manage additional API documents like guides and API Recipes to help developers better understand the use cases supported by the API. 

Last but not least, authorization is automatically applied to critical API documentation resources, maintaining a level of API confidentiality where required.

See for yourself what Akana can do for you, from API documentation to your portal — and beyond.

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This blog was originally published on August 31, 2020, and has since been updated for accuracy and relevance.