Factorio Forums

I've found some Factorio mods have improved the game to such a degree (not that the vanilla game isn't already extraordinary, mind you) that I feel a bit guilty at receiving them for free. In particular, it's clear that some modders have spent hundreds of hours or more, and it shows in the creativity and polish of their mods.

So, my question: Is there a way to show monetary appreciation for excellent mods?

Is this allowed (or at least not prohibited) by the Factorio license?

I know some bloggers have links saying things like "If this helped you, you might consider buying me a cup of coffee." I can see where Factorio modders might have something similar, where those of us who've gotten hour upon hour of enjoyment from their mods could say thank you with more than just effusive words, and perhaps the most popular modders might even be able to make a living off their work.

Some modders have Patreon pages, or give a link to their paypal, or publish under beerware licensing.
If one is sincerely willing to compensate modders for their hard work, and the modders are accepting donations, it's fairly easy to find the way to do so.