Arm and our partners are working together to make it simpler and easier for developers to build and update IoT applications across a diverse range of MCU hardware platforms. Our immediate focus is to make sure every MCU device has the capability to update its firmware securely, whatever IoT stack and RTOS it is running. To do this we've worked with partners across the ecosystem to define a secure device update interface: the PSA Firmware Update API. We've worked with the same partners to agree on a set of supporting APIs that make it easy to run the same application across both virtual and physical platforms.. Taken together these pieces form the basis of a Common Device Interface for running IoT applications on MCU, which we call the Open-CMSIS-CDI. In this presentation we'll talk about the major pieces of Open-CMSIS-CDI, the essential aspects of PSA Firmware Update and the way we're delivering this with partners. We'll also showcase real applications which use standards and CDI today and highlight the ways you can do the same.