typeSirkel is free, with no paid plan and no ads, and it will stay that way. I build it in the hours around my other work.
If it has made your writing a little lighter and you would like to give something back, a small tip goes straight into keeping it going: time for new features, the domain and the relay that carries shared drafts, and an Apple developer account so the Mac app opens without warnings.
Not in a position to give right now? That is completely fine. A star on GitHub, a bug report, or telling a friend helps just as much.