Flash now has a poor reputation, both for excessive resource requirements and for frequent security vulnerabilities. Although HTML5 was available in 2012, it lacked robust development tools and browser compatibility was less widespread. Most modern browsers are compatible with HTML5, including browsers on mobile devices where Flash is not an option.

The first HTML5 interface for ESXi came in the form of a VMware Fling. VMware publishes a variety of internally developed tools and utilities as Flings. These tools do not have commercial support and are released on a user-beware basis. This is a great way to test customer acceptance and gauge demand for new features.

During this trial period, the HTML5 Host Client Fling was warmly welcomed by the VMware community. Those of us with a long VMware history remember the Management User Interface, a very basic HTML interface for configuring a single ESX 2.x server. The new HTML5 implementation allows comprehensive standalone host configuration and operation, as well as VM creation and management. It will replace the vSphere Client for managing a standalone ESXi server. With the release of ESXi 6.0 Update 2, the Host Client has become a feature of ESXi with full support. We will not see the Windows vSphere Client updated for newer versions of ESXi now that the Host Client is available.