Sorry, since this was posted a month ago (https://news.ycombinator.com/item?id=28854949) highlighting that it was sponsorware. It is now open-sourced and free also.
``` Simply stated, the “Sponsorware” model for releasing a project is made up of a few simple steps:
Build something people want! – This is easier said than done, but we believe this model works best for open source projects with significant pre-release hype. The more interest you are able to build in your product before launch, the better your results are likely to be.
Make it available only to “sponsors” – These “sponsors” are people who give you recurring revenue. This can be through any of the big sponsorship platforms (i.e. - GitHub Sponsors, Patreon, OpenCollective, etc.) or it can be a system you roll yourself. The important parts are A) that the revenue is recurring, and B) that either your number of sponsors or your net revenue is publicly viewable
Set a sponsorship threshold, and after crossing it, make your thing freely available to the world! – This can be a number of monthly sponsors, an amount of monthly revenue, or whatever you like. It should be PUBLIC though. Transparency is huge in this process and people need to be able to see progress toward the goal.I'm up to 211 sponsors, about $1700 per month.
Many of those sponsors are one-time donations. At the beginning, I set the minimum one-time donation to $1; once I reached 100 sponsors, I bumped the minimum up to $10.
The larger sponsors come mostly from digital ink library perfect-freehand (https://github.com/steveruizok/perfect-freehand), also MIT licensed, which is being used by many products such as Next.js live, Milanote, Clover, etc.
[1]: https://unglue.it/