Open source licencing The Qt library can be used under open source licencing using the LGPL licence. Some parts ar GPL, but most is LGPL, so your application source code can remain proprietary as long as you don’t use the GPL bits. See these Qt pages: https://www.qt.io/download-open-source https://www.qt.io/licensing/open-source-lgpl-obligations Downloading the open source library https://www.qt.io/download-open-source#source

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