Approaches for executing untrusted software on a client without compromising the client using micro-virtualization to execute untrusted software in isolated contexts. A template for instantiating a virtual machine on a client is identified in response to receiving a request to execute an application. After the template is identified, without human intervention, a virtual machine is instantiated, using the template, in which the application is to be executed. The template may be selected from a plurality of templates based on the nature of the request, as each template describe characteristics of a virtual machine suitable for a different type of activity. When the client determines that the application has ceased to execute, the client ceases execution of the virtual machine without human intervention.