Techniques for securely instantiating applications associated with computing resource service provider services on hardware that is controlled by third parties and/or customers of the computing resource service provider are described herein. A request to instantiate an application is received and fulfilled by selecting a computer system from computer systems that are controlled by a third party and/or a customer of the computing resource service provider. The computer system is selected based at least in part on the hardware capabilities of the computer system associated with instantiating a secure execution environment. The application is then instantiated within a secure execution environment operating on the computer system.