Journal of E-Technology Barbu Paul - Gheorghe 8 3 2017 http://www.dline.info/jet/fulltext/v8n3/jetv8n3_1.pdf This paper aims to describe a bootloader for embedded devices. The purpose of the bootloader is to be the first to run when the microcontroller starts and to provide a way of controlling what application runs next, similarly to how bootloaders work on the desktop systems. The difference here being that the bootloader’s purpose is to allow the embedded device to be much more flexible, since the application running on the microcontroller can be changed without using specialized hardware. This flexibility and the fact that no specialized hardware programmers are needed also leads to a reduction of costs for deploying and maintaining the embedded systems. These two goals, flexibility and cost reduction must be accompanied by a third one: security. The recent growth of embedded systems in the IoT (Internet of Things) domain demands that the device deployed be more secure than in the past.