API versioning is a critical aspect of API design, allowing developers to manage changes and maintain compatibility with existing client applications. One popular strategy for API versioning is to use subdomains. This approach can help in organizing different versions of an API while keeping them easily accessible.
In subdomain-based versioning, different versions of an API are hosted on different subdomains. For example, you might have the following structure:
This method allows you to clearly delineate between versions and can make it easier for developers to switch between them.
https://v1.api.example.com/users
https://v2.api.example.com/users
In this example, both versions of the API provide access to user data. The client can specify which version they want to interact with by referencing the corresponding subdomain.
https://v1.api.example.com/orders
https://v2.api.example.com/orders
Here, version 1 of the API has its own endpoint for orders, which may function differently than version 2. For instance, version 2 might include additional fields or a different data structure.
When deprecating an older version, you can still maintain access through the subdomain while encouraging users to migrate:
https://v1.api.example.com (Deprecated)
https://v2.api.example.com (Active)
In this case, clients are informed that version 1 is deprecated and should move to version 2 for continued support and new features.
You can also implement wildcard subdomains for handling multiple versions:
https://*.api.example.com
This approach allows flexibility in creating new versions without altering the core domain structure. For instance, if you decide to launch a beta version:
https://beta.api.example.com
Using subdomains for API versioning is an effective way to manage different versions of your API while providing a clear and organized structure. By following the examples outlined above, you can implement this strategy in your own projects, ensuring better version control and user experience.