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I would like to use Qt in personal projects but the one thing that prevents me to do it is the license. If I want to monetize an app, I must purchase the Qt license.

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There's nothing in even the GPL (let alone LGPL) forbidding monetization, and the LGPL doesn't even require you to release your source code if you're dynamically linking Qt.

> and the LGPL doesn't even require you to release your source code if you're dynamically linking Qt.

Can you elaborate?

Sure.

The (L)GPL requires "derivative works" to be licensed under the same terms as the original. The LGPL contains an exemption for works which reference the original as a dynamic library (.dll, .so, .dylib, etc.), such that (unlike with the GPL) non-LGPL software can use LGPL libraries. In other words: if your program only dynamically links against Qt, then it is not a "derivative work" and therefore doesn't have to be licensed under Qt's own license terms.

Qt does have GPL modules that are expansions, like QtCharts. Any extra module, be careful to only choose LGPL.

Then what do you use?

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