Versioning formats for REST APIs

To allow the client to request a particular API version, there are three common ways you can do this.

It can be done as part of the URI:

https://myserver.com/v1/helloworld 

It can also be done as a query string parameter:

https://myserver.com/helloworld?api-version=1 

Finally, It can be done by using a custom HTTP header:

GET https://myserver.com/helloworld
api-version: 2

Whichever way you implement versioning is up to you and your team, but it should play a big part in your upfront design thinking. Once you have decided on an option stick, to it as providing a consistent and great experience for your consumers should be one of your primary goals.