Releases and Active Development
  • The current release is 4.11.3 (download here).
  • The next release branch is 5. For details and status, visit the Release page. Note that this release branch was planned to be 4.12 but significant changes warranted bumping the major number (e.g. 4 to 5). The new release numbering scheme is described here.
  • Information on older releases is available here.

What is RTEMS?

The Real-Time Executive for Multiprocessor Systems or RTEMS is an open source Real Time Operating System (RTOS) that supports open standard application programming interfaces (API) such as POSIX. It is used in space flight, medical, networking and many more embedded devices using processor architectures including ARM, PowerPC, Intel, Blackfin, MIPS, Microblaze and more. Commercial support is available from US and European companies, and free support comes via the active global community. Major decisions about RTEMS are made by the core developers in concert with the user community, guided by the Mission Statement. We provide access to our development sources via a Git Repository (see these Instructions for details). We strive to provide regular, high-quality releases, which we want to work well on a wide range of embedded targets using cross development from a variety of hosts including GNU/Linux distributions, MS Windows, BSDs, Solaris, and Mac OS. We encourage everyone to contribute changes and feedback to RTEMS.


January 14, 2020

The 2019 edition of the Flight Software Workshop was held in Huntsville Alabama, home of OAR Corporation. This FSW was a huge success with great presentations. The presentations included discussions of many interesting projects using RTEMS. The...

December 14, 2019

Matthias Göbel passed along information about the ESA Brave Days ( password BRAVEDAYS-2019) and the GR740 User Day (...

March 19, 2019

The European Space Agency is sponsoring the pre-qualification of RTEMS for space applications. As part of this effort, embedded brains GmbH has prepared a...

January 04, 2019

OAR is planning to host the RTEMS Training class at the OAR Corporate office in Huntsville, AL, USA.

This training session is open to anyone interested in learning specifically about RTEMS, or about real-time, embedded systems in general. Monday is a Kick Start day for learning about and...

August 07, 2018

The RTEMS Foundation has received a letter from On-Line Applications Corporation (OAR) which grants the RTEMS Community permission to relicense OAR's current and future contributions. The letter is attached as a PDF to ticket 3053 and the text of the...