What is API Design?

API design is the process of defining and documenting the interactions between software components. This involves defining different endpoints, specifying all the formats to be used, and defining the behavior of any software that forms part of the API.  Specifically, a designed API has a special significance for how systems interact with one another and what kind of interaction proves successful. 

It is superficial to conclude that the choice of API facilitates multipartite communication, and its clarity and effectiveness may determine software complexity. People often fail to realize that designing an API involves several repetitions, especially in situations where sensitive data is being dealt with. This requires a lot of testing to ensure the system is both resistant and protected.

APIs are, therefore, classified depending on accessibility, structure, and protocols used. Here’s a breakdown of these API types and their characteristics: 

• Availability: APIs can be either Public (in this case, these APIs are available to anyone) or Private (they are made available to a limited number of users or organizations).
• Architecture: APIs can indeed be RESTful and often use HTTP, as well as SOAP, which is an older XML-based protocol.   
• Protocols: APIs can also be categorized by the underlying protocol, with Web APIs being over the internet and the newly introduced GraphQL being optimized for data querying, among others.

When designing APIs, adherence to certain standards and best practices, such as RESTful design principles, selecting the appropriate HTTP method, API versioning, and data caching. These measures may affect aspects such as access, reliability, and extendibility of APIs, possibly with an eye on achieving improved usability. 

When HTTP verbs are utilized properly and accurately, it becomes more efficient in describing the operation that should be completed on the particular resource. Version control is important for maintaining compatibility with your existing integrations while making changes.

Choosing the right tool to use in creating your API is one of the most crucial aspects if you want a seamless development process. Understanding the capabilities and limitations of popular platforms like Stoplight, SwaggerHub, and Apigee facilitates informed decision-making for choosing the best option. 

• Stoplight: Stoplight’s visual editor is intended to facilitate the creation and iteration of API specifications, thus influencing team workflow.  It contains features in its functionality that work side by side with reference to mock and collaborative aspects concerning emulation relating to live scenarios. Stoplight’s API documentation tools are potentially used to maintain accurate and current references. 
• SwaggerHub: This is a platform designed for API documentation and collaboration.  Due to templates, the user can modify documentation style and format, which can influence usability and information density. SwaggerHub’s version control capabilities are correspondingly tied to the API development cycle. The platform’s collaboration features could extend, support, or facilitate interaction and information sharing amongst the users or in particular teams.
• Apigee: Apigee is a platform specifically for managing APIs and accompanies them with a base of security and governance. As such, despite the amount of capabilities it presents, the API might also be intricate enough to require more steps for implementation by teams that are small or that are relatively inexperienced in API design. For some organizations, the cost of Apigee may necessitate a thorough evaluation of their budget. 

API versioning is the management of change within an API over time.  It’s kind of like releasing a new edition of a book, where the previous version isn’t discarded. This is important for your API to remain compatible and for any application that is using your API to still be able to run as you include new functions, fixes or even complete overhaul of your API.

Here are common API versioning strategies:

• URI Versioning: It is set in the URL. (e.g., /v1/users, /v2/users). This is easy to grasp but can result to several URLs possible.
• Header Versioning: The version is transmitted in a request header for example (e.g., API-Version: v2). This makes URLs clean but puts the header in the hands of clients.
• Query Parameter Versioning: It becomes an argument appended to the URL as a query string (e.g., /users?version=2). Less difficult to implement than intermediary ones, but not always clear.
• Content Negotiation: The client indicates the required version of the response format using the Accept header. This is flexible but slightly more difficult to implement as compared to the fixed.