How to Write a Standard API Document

Basic elements for writing excellent API documentation include document structure, API design, example code, etc. With this article, learn how to write a high-quality API documentation.

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How to Write a Standard API Document

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To understand how to start writing a qualified API document, you need to first understand what an API is, what its use cases are, and what capabilities it should have.

What is API?

Imagine that when Person A buys a new computer, they want to extend the display screen to a color-accurate monitor. Person A can use an HDMI cable to connect the monitor to the computer's HDMI port, and the black screen instantly displays a vivid image. In this process, Person A does not need to know what parameters are used to transmit the image between the screen and the computer, nor do they need to understand the logic behind the screen's color display. They only need to know how to use the simple HDMI interface to meet their needs.

Similar to HDMI, an API (Application Programming Interface) is essentially a virtual port. Two products follow the same set of information communication protocols, and after successfully pairing, multiple functions are integrated to work together, achieving an effect where 1+1 > 2.

How to Use an API?

The answer is, of course, to read the API interface document to understand how to use the API. When using an unfamiliar interface for the first time, you need a clear and detailed functional manual to help understand how the interface works. This is the role of an API document. An API document is a specification that describes how an application programming interface (API) works and provides all the information needed to use the API.

You can think of an API document as a roadmap or map. It tells users how to get to where they want to go. Like a map, an API document requires clear and detailed explanations, including milestones, transportation methods, and route markers, so that users can easily find the information they need and use the API correctly.

What Elements Should an API Document Have?

An API document should include basic information about the interface, such as the interface name, version, and author. Additionally, it should also contain detailed information on how the interface works, such as request and response formats, supported request parameters, error codes, and more. In addition, the interface document should provide sample code to help users better understand how to use the API.

  • Interface Overview

Briefly introduce the purpose and function of the interface, just like looking at a menu in a restaurant. The menu can tell customers which dishes are available, and the API document can tell developers which interfaces can be called. The detailed description on the menu can let customers understand the characteristics and methods of each dish, and the API document also provides detailed descriptions and examples for developers to understand how to call the interface and use the data returned by the interface.

  • Interface Address

The interface address tells developers where to use the interface service.

Interface Address
  • Request Parameters

List all available parameters and their descriptions, such as the type, default value, and restriction conditions of each parameter.

Request Parameters
  • Response Format

List the response format for each interface, including status codes, data structures, and data types.

Response Format
  • Response Example

Provide example code and data for using the API to help developers better understand how to use the API.

Response Example
  • Version Control

As the functionality of the API evolves, modifications may be made to the interface, such as adding, deleting, or changing parameters, or changing the format of the returned results. If version control is not available in the API documentation, data loss may occur, and new changes may affect users' API usage experiences, causing service anomalies for existing users.

Version Control

Make Writing API Documents Easy with Apidog

Writing API Documents is Simple with ApidogOne of the keys to an API's effectiveness is effective documentation. Users are likely to run into issues without clear and comprehensive instructions, which might result in application failures. As a result, make sure your API documentation is simple to read and use when you develop it. A more sophisticated tool for API design, development, and testing, Apidog is an integrated platform for API collaboration that can perform API documentation, API debugging, API Mock, and API automated testing. Designing a qualified API interface document is no longer challenging thanks to Apidog.