We are offering our top tiers (Ultimate or Gold) for free to open source projects [1]. You can see the complete list in our repo [2]. Some of the most recent projects that received our free license are Arch Linux, the Tor Project, edX (currently migrating). Just to add a few more: Drupal, Haskell, VLC, Kali Linux, Lineage OS, and more on this comment [3].
Part of the application for open source projects here requires you specify how many "seats" you need.
> The number of seats is the number of different users that will use this license in the next year.
This seems counter to how many open source projects work where contributors come out of nowhere to make a contribution and may or may not stick around. How does this work when you have hundreds or thousands of unique contributors a year, and you have no good way of predicting?
IIRC seats are calculated based on monthly active users, and are a soft cap: we've outgrown our license, so we will have to retroactively buy the missing seats on our next license renewal.
I expect this is no different from a OS license, except that that OS project doesn't pay for the license.
> The number of seats is the number of different users that will use this license in the next year.
This seems counter to how many open source projects work where contributors come out of nowhere to make a contribution and may or may not stick around. How does this work when you have hundreds or thousands of unique contributors a year, and you have no good way of predicting?