According to this reddit thread [0], some important parts of Qt are not Free and Open Source software. That includes the Qt Quick compiler. It's true that some

According to this reddit thread [0], some important parts of Qt are not Free and Open Source software. That includes the Qt Quick compiler. It's true that some of what's under the 'Qt' umbrella, is available under the permissive 'weak copyleft' LGPL licence. More generally: When a library is released under a strong copyleft licence like the GPL, then you are welcome to make use of it, but you are required to release your software under that same licence (i.e. to make it Free and Open Source), if you publicly release it. They do not prohibit you from making money, nor do they single out large corporations for special hostile treatment. Any licence that does, is unlikely to be considered a Free Software licence, or an Open Source licence. (The AGPL licence goes even further than the GPL, and can apply even if you don't release your software. This is relevant for the software-as-a-service model.) [0] https://www.reddit.com/r/programming/comments/803fx9/qt_commercial_vs_free_question_in_comment/ https://www.reddit.com/r/programming/comments/803fx9/qt_comm...