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Last site update June 02 2015


The Market Leading, De-facto Standard and Cross Platform Real Time Operating System (RTOS). Don't Let Your RTOS Lock You In.

Immediate Free Download and Use * Feature Rich * Tiny Footprint * Easy To Use Pre-configured Projects * Can Be Used In Commercial Applications * Massive User Community * Free Support * Optional Commercial Licensing/Support * Strict Coding Standard * Safety Critical Version Available * Tickless Mode for Low Power Applications

Developed in partnership with the world's leading chip companies over a 12 year period, FreeRTOS is the market leading real time operating system (or RTOS), and the de-facto standard solution for microcontrollers and small microprocessors.

With millions of deployments in all market sectors, blue chip companies trust FreeRTOS because it is professionally developed, strictly quality controlled, robust, supported, free to use in commercial products without a requirement to expose proprietary source code, and has no IP infringement risk.

The FreeRTOS value proposition (why use anything else?) . . .
Things you might not know about FreeRTOS . . .
Why choose FreeRTOS? . . .

World's Most Innovative IoT Solution

"We provide the infrastructure that enables your innovation"

Real Time Engineers Ltd have partnered with Nabto to develop FreeRTOS+Nabto, a product that brings simplicity, platform independence, and entry level access to Nabto's peer to peer Internet of Things solution.

FreeRTOS+Nabto is a small piece of C code (23K inclusive of FreeRTOS and the UDP only IP networking stack) that, when integrated into an embedded networked device, allows that device to be remotely accessed and controlled using a rich web based user interface or intelligent data acquisition system.

See how we solve the challenges posed by the Internet of Things . . .

Best in Class RTOS Trace Tools

One of more than 20 trace views. Click to enlarge.

FreeRTOS+TraceTM (part of the FreeRTOS+ ecosystem showcase) is a sophisticated trace tool for FreeRTOS. With more than 20 graphically interconnected views, FreeRTOS+Trace provides a world leading level of insight into the run-time behaviour of your FreeRTOS application. It has become an indispensable debugging and optimisation tool.

Commercial Licensing & Middleware

OpenRTOS is a commercially licensed and supported version of FreeRTOS that includes fully featured professional grade USB, file system and TCP/IP components. OpenRTOS is provided by a global engineering company under license from Real Time Engineers Ltd.
Safety Critical Applications

SafeRTOS (part of the FreeRTOS+ ecosystem showcase) is a SIL3 TUV certified RTOS for the safety critical market. SafeRTOS is provided by a global engineering company under license from Real Time Engineers Ltd.

SafeRTOS is delivered as source code, with as much or little certification evidence as required. Certification packs and design history files are available that specifically target applications that fall under IEC 61508, EN62304 and FDA 510(k) regulatory requirements.

SafeRTOS has been specifically designed for the (primarily 32-bit) microcontroller market, resulting in a design that is highly optimised for use in applications where a small code size footprint is essential. The SafeRTOS ROM footprint is typically in the 7K to 14K bytes range.

FreeRTOS Masterclass Training

Investing in training allows your team to be as productive as possible as early as possible, lowering your overall development cost, and enabling you to bring a more robust product to market earlier than would otherwise be possible.

The FreeRTOS Masterclass course is presented by Real Time Enigneers Ltd's CTO Richard Barry, who is both the architect and key author of FreeRTOS, and so also the world's leading authority on what is the world's most popular real time kernel for deeply embedded MCU designs.

Obtaining your training from Richard ensures your team will gain directly from his in-depth and leading edge product knowledge, and years of usage experience.

Masterclass training can be tailored to your needs.


Did you know?

  • FreeRTOS is downloaded every 260 seconds (on average).
  • FreeRTOS came top in class in the 2011, 2012, 2013, 2014 and 2015 EETimes embedded systems market surveys in two categories: The RTOS kernel currently being used, and the RTOS kernel being considered for the next project!
  • FreeRTOS offers lower project risks and a lower total cost of ownership than commercial alternatives because:
    • It is fully supported and documented.
    • Most people take products to market without ever contacting us, but with the complete peace of mind that they could opt to switch to a fully indemnified commercial license (with dedicated support) at any time.
  • Some FreeRTOS ports never completely disable interrupts.
  • For strict quality control purposes, and to remove all IP ownership ambiguity, official FreeRTOS code is separated from community contributions.
  • FreeRTOS has a tick-less mode to directly support low power applications.
  • FreeRTOS was downloaded >113000 times in 2014.
  • FreeRTOS is designed to be simple and easy to use: Only 3 source files that are common to all RTOS ports, and one microcontroller specific source file are required, and its API is designed to be simple and intuitive.
  • The RL78 port can create 13 tasks, 2 queues and 4 software timers in under 4K bytes of RAM!


Why choose FreeRTOS?

"It's probably safe to say at this point that FreeRTOS goes through more 'peer-review' than any other RTOS available on the planet. I have used it in several projects - one of which was a multiprocessor environment that used more than 64 processors and needed to run for months reliably. The RTOS core performed well. Take FreeRTOS for a spin." - John Westmoreland

FreeRTOS is a risk free choice, providing the best of all worlds: FreeRTOS is truly free and supported, even when used in commercial applications. The FreeRTOS open source license does not pose any risk to your proprietary software. You can take a product to market using FreeRTOS without even talking to us, let alone paying any fees, and thousands of people do just that. If, at any time, you would like to receive additional backup, or if your legal team require additional written guarantees or indemnification, then there is a simple low cost commercial upgrade path. Your peace of mind comes with the knowledge that you can opt to take the commercial route at any time you choose.

Here are some reasons why FreeRTOS is a good choice for your next application - FreeRTOS...

  • Provides a single and independent solution for many different architectures and development tools.
  • Is known to be reliable. Confidence is assured by the activities undertaken by the SafeRTOS sister project.
  • Is feature rich and still undergoing continuous active development.
  • Has a minimal ROM, RAM and processing overhead. Typically an RTOS kernel binary image will be in the region of 6K to 12K bytes.
  • Is very simple - the core of the RTOS kernel is contained in only 3 C files. The majority of the many files included in the .zip file download relate only to the numerous demonstration applications.
  • Is truly free for use in commercial applications (see license conditions for details).
  • Comes with a porting, platform development, or application development service should it be required.
  • Is well established with a large and ever growing user base.
  • Contains a pre-configured example for each port. No need to figure out how to setup a project - just download and compile!
  • Has an excellent, monitored, and active free support forum.
  • Has the assurance that commercial support is available should it be required.
  • Provides ample documentation.
  • Is very scalable, simple and easy to use.
  • FreeRTOS offers a smaller and easier real time processing alternative for applications where eCOS, embedded Linux (or Real Time Linux) and even uCLinux won't fit, are not appropriate, or are not available.

FreeRTOS Announcements Mailing List

You can keep up to date with very occasional FreeRTOS announcements by adding yourself to the FreeRTOS mailing list. Emails are infrequent and kept short. We respect your privacy, so do not provide email addresses to any third party. Every email sent contains unsubscribe instructions.

NEW: You can also now follow FreeRTOS on Twitter for instant notifications.

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Copyright (C) 2004-2010 Richard Barry. Copyright (C) 2010-2015 Real Time Engineers Ltd.
Any and all data, files, source code, html content and documentation included in the FreeRTOSTM distribution or available on this site are the exclusive property of Real Time Engineers Ltd.. See the files license.txt (included in the distribution) and this copyright notice for more information. FreeRTOSTM and FreeRTOS.orgTM are trade marks of Real Time Engineers Ltd.

Latest News - New Book Edition!

Receive a complimentary pre-release pdf of our up-coming book "Mastering the FreeRTOS Real Time Kernel, a Hands-On Tutorial Guide" with every purchased copy of the existing "Using the FreeRTOS Real Time Kernel" book.

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FreeRTOS Partners

ARM Connected RTOS partner for all ARM microcontroller cores

Renesas Electronics Gold Alliance RTOS Partner.jpg

Microchip Premier RTOS Partner

RTOS partner of NXP for all NXP ARM microcontrollers

Atmel RTOS partner supporting ARM Cortex-M3 and AVR32 microcontrollers

STMicro RTOS partner supporting ARM7, ARM Cortex-M3, ARM Cortex-M4 and ARM Cortex-M0

Xilinx Microblaze and Zynq partner

Altera RTOS partner for Nios II and Cortex-A9 SoC

Freescale Alliance RTOS Member supporting ARM and ColdFire microcontrollers

Infineon ARM Cortex-M microcontrollers

Texas Instruments MCU Developer Network RTOS partner for ARM and MSP430 microcontrollers

Cypress RTOS partner supporting ARM Cortex-M3

Fujitsu RTOS partner supporting ARM Cortex-M3 and FM3

Microsemi (previously Actel) RTOS partner supporting ARM Cortex-M3

Atollic Partner

IAR Partner

Keil ARM Partner

Embedded Artists

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