Documentation → Introduction → Author and License
Author and License
Copyright (c) Vitaliy Filippov (vitalif [at] yourcmc.ru), 2019+
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All server-side code (OSD, Monitor and so on) is licensed under the terms of Vitastor Network Public License 1.1 (VNPL 1.1), a copyleft license based on GNU GPLv3.0 with the additional "Network Interaction" clause which requires opensourcing all programs directly or indirectly interacting with Vitastor through a computer network and expressly designed to be used in conjunction with it ("Proxy Programs"). Proxy Programs may be made public not only under the terms of the same license, but also under the terms of any GPL-Compatible Free Software License, as listed by the Free Software Foundation. This is a stricter copyleft license than the Affero GPL.
Please note that VNPL doesn't require you to open the code of proprietary software running inside a VM if it's not specially designed to be used with Vitastor.
Basically, you can't use the software in a proprietary environment to provide its functionality to users without opensourcing all intermediary components standing between the user and Vitastor or purchasing a commercial license from the author 😀.
Client libraries (cluster_client and so on) are dual-licensed under the same VNPL 1.1 and also GNU GPL 2.0 or later to allow for compatibility with GPLed software like QEMU and fio.