So many of these "freemium" things will spam you relentlessly asking you to upgrade.

This one doesn't have the best history either, although it's officially open source, at least at one point the build system was private[0]. I've not kept up with the drama, so I have no idea if that is still the case.

[0] https://github.com/FortAwesome/Font-Awesome/issues/12199#iss...