The advantage of open source licenses is that we don't have to pay anyone to use Qt; however, the downside is that there are some limitations imposed on how it can be used.
When choosing the open source edition, we have to choose between GPL 3.0 and LGPL 3. Since LGPL is more liberal, in this chapter we will focus on it. Choosing LGPL allows you to use Qt to implement systems that are either open source or closed source—you don't have to reveal the sources of your application to anyone if you don't want to.
However, there are a number of restrictions you need to be aware of:
- Any modifications that you make to Qt itself need to be made public, for example, by distributing source code patches alongside your application ...