> Namespacing by version also is pretty "clean." Imagine updating your API in the future without the namespace. You'd have to implement the version in some diff

> Namespacing by version also is pretty "clean." Imagine updating your API in the future without the namespace. You'd have to implement the version in some difficult way (for the end developer) such as during authentication or as a request param or cookie or something ridiculous. Why? Assuming the author is actually using REST, worst case for updating is adding another resource somewhere. There should be no need to update client applications at all.