L4Re is an open-source operating system and hypervisor framework built around an L4 microkernel and developed by Kernkonzept. It comprises the microkernel, core foundation, OS services and libraries, and targets automotive, security-critical systems, secure cloud infrastructure and embedded use. A hypervisor and a micro-hypervisor for small MPU-based systems are also available. The framework runs on MPU and MMU systems and supports Arm Cortex-A and Cortex-R as well as RISC-V. The source code is available through l4re.org and GitHub; Kernkonzept additionally offers consulting, development, support, maintenance and training.
Kernkonzept GmbH is a mid-sized company in Dresden, Germany, which started in 2012 as a spin-off from the Technische Universität Dresden. The pages consulted name no foreign parent company. Since 15 September 2025, L4Re has been released under the MIT licence instead of GPLv2. Because you deploy the software yourself on your own hardware, there is no mandatory cloud service and your data stays under your own control. For European organisations it is a European option alongside North American embedded operating systems such as QNX.