Calva is open source and free to use. It is actively maintained during our free time, and it keeps improving. You can contribute in many different ways, one of which is sponsoring. These are our sponsor profiles:
If you are working at a company which benefits from Calva's existence and continued development, please consider sponsoring at the Calva Gold Sponsor tier.
Please see this statement from Cognitect about the importance of supporting open source developers.