---
key: freertos-exception-2.0
short_name: FreeRTOS exception to GPL 2.0
name: FreeRTOS exception to GPL 2.0
category: Copyleft Limited
owner: FreeRTOS
is_exception: yes
spdx_license_key: freertos-exception-2.0
faq_url: https://aws.amazon.com/blogs/opensource/announcing-freertos-kernel-v10/
other_urls:
    - http://www.freertos.org/
    - http://www.freertos.org/a00114.html
    - http://www.freertos.org/a00114.html#exception
    - https://web.archive.org/web/20060809182744/http://www.freertos.org/a00114.html
standard_notice: |
    The FreeRTOS source code is licensed by a modified GNU General Public
    License - the modification taking the form of an exception.
    The exception permits the source code of applications that use FreeRTOS
    solely through the API published on this website to remain closed source,
    thus permitting the use of FreeRTOS in commercial applications without
    necessitating that the whole application be open sourced. The exception can
    only be used if you wish to combine FreeRTOS with a proprietary product and
    you comply with the terms stated in the exception itself.
    The FreeRTOS download also includes demo application source code, some of
    which is provided by third parties AND IS LICENSED SEPARATELY FROM
    FREERTOS.
    For the avoidance of any doubt refer to the comment included at the top of
    each source and header file for license and copyright information.
    This is a list of files for which Real Time Engineers Ltd. is not the
    copyright owner and are NOT COVERED BY THE GPL.
    1. Various header files provided by silicon manufacturers and tool vendors
    that define processor specific memory addresses and utility macros.
    Permission has been granted by the various copyright holders for these
    files to be included in the FreeRTOS download. Users must ensure license
    conditions are adhered to for any use other than compilation of the
    FreeRTOS demo applications.
    2. The uIP TCP/IP stack the copyright of which is held by Adam Dunkels.
    Users must ensure the open source license conditions stated at the top of
    each uIP source file is understood and adhered to.
    3. The lwIP TCP/IP stack the copyright of which is held by the Swedish
    Institute of Computer Science. Users must ensure the open source license
    conditions stated at the top of each lwIP source file is understood and
    adhered to.
    4. Various peripheral driver source files and binaries provided by silicon
    manufacturers and tool vendors. Permission has been granted by the various
    copyright holders for these files to be included in the FreeRTOS download.
    Users must ensure license conditions are adhered to for any use other than
    compilation of the FreeRTOS demo applications.
    5. The files contained within FreeRTOS\Demo\WizNET_DEMO_TERN_186\tern_code,
    which are slightly modified versions of code provided by and copyright to
    Tern Inc.
    Errors and omissions should be reported to Richard Barry, contact details
    for whom can be obtained from the Contact page.
    This library is free software; you can redistribute it and/or modify it
    under the terms of the GNU General Public License as published by the Free
    Software Foundation; either version 2, or (at your option) any later
    version.
    This library is distributed in the hope that it will be useful, but WITHOUT
    ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
    FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
    more details.
    You should have received a copy of the GNU General Public License along
    with this library; see the file COPYING. If not, write to the Free Software
    Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
    GNU General Public License Exception
    Any FreeRTOS source code, whether modified or in its original release form,
    or whether in whole or in part, can only be distributed by you under the
    terms of the GNU General Public License plus this exception. An independent
    module is a module which is not derived from or based on FreeRTOS.
    EXCEPTION TEXT:
    Clause 1
    Linking FreeRTOS statically or dynamically with other modules is making a
    combined work based on FreeRTOS. Thus, the terms and conditions of the GNU
    General Public License cover the whole combination.
    As a special exception, the copyright holder of FreeRTOS gives you
    permission to link FreeRTOS with independent modules that communicate with
    FreeRTOS solely through the FreeRTOS API interface, regardless of the
    license terms of these independent modules, and to copy and distribute the
    resulting combined work under terms of your choice, provided that
    1. Every copy of the combined work is accompanied by a written statement
    that details to the recipient the version of FreeRTOS used and an offer by
    yourself to provide the FreeRTOS source code (including any modifications
    you may have made) should the recipient request it.
    2. The combined work is not itself an RTOS, scheduler, kernel or related
    product.
    3. The independent modules add significant and primary functionality to
    FreeRTOS and do not merely extend the existing functionality already
    present in FreeRTOS.
    Clause 2
    FreeRTOS may not be used for any competitive or comparative purpose,
    including the publication of any form of run time or compile time metric,
    without the express permission of Real Time Engineers Ltd. (this is the
    norm within the industry and is intended to ensure information accuracy).
---

EXCEPTION TEXT:

Clause 1
Linking FreeRTOS statically or dynamically with other modules is making a combined work based on FreeRTOS. Thus, the terms and conditions of the GNU General Public License cover the whole combination.

As a special exception, the copyright holder of FreeRTOS gives you permission to link FreeRTOS with independent modules that communicate with FreeRTOS solely through the FreeRTOS API interface, regardless of the license terms of these independent modules, and to copy and distribute the resulting combined work under terms of your choice, provided that
1. Every copy of the combined work is accompanied by a written statement that details to the recipient the version of FreeRTOS used and an offer by yourself to provide the FreeRTOS source code (including any modifications you may have made) should the recipient request it.
2. The combined work is not itself an RTOS, scheduler, kernel or related product.
3. The independent modules add significant and primary functionality to FreeRTOS and do not merely extend the existing functionality already present in FreeRTOS.

Clause 2
FreeRTOS may not be used for any competitive or comparative purpose, including the publication of any form of run time or compile time metric, without the express permission of Real Time Engineers Ltd. (this is the norm within the industry and is intended to ensure information accuracy).