MCUboot is a secure bootloader for 32-bit MCUs. The goal of MCUboot is to define a common infrastructure for the bootloader, system flash layout on microcontroller systems, and to provide a secure bootloader that enables easy software upgrade.

MCUboot is operating system and hardware independent and relies on hardware porting layers from the operating system it works with. Currently MCUboot works with both the Apache Mynewt, and Zephyr operating systems, but more ports are planned in the future. RIOT is currently supported as a boot target with a complete port planned.

MCUboot is an open governance project. See the membership list for current members, and the charter for more details.


There is also a document about signed images that is out of date. You should use instead of these documents.


The issues being planned and worked on are tracked using GitHub issues. To participate please visit:

MCUboot Issues

~~Issues were previously tracked on MCUboot JIRA , but it is now deprecated.~~


Information and documentation on the bootloader is stored within the source.

~~It was previously also documented on confluence: Confluence page , but it is now deprecated and not currently maintained~~

For more information in the source, here are some pointers:

  • boot/bootutil: The core of the bootloader itself.

  • boot/boot_serial: Support for serial upgrade within the bootloader itself.

  • boot/zephyr: Port of the bootloader to Zephyr

  • boot/mynewt: Mynewt bootloader app

  • boot/mbed: Port of the bootloader to Mbed-OS

  • imgtool: A tool to securely sign firmware images for booting by MCUboot.

  • sim: A bootloader simulator for testing and regression


Developers welcome!