I'd love a solid open source version of calendly.

The co-founders are nice people and I have a years worth of the premium version. Unfortunately, too buggy and people end up booking at the wrong hour, multiple-events gets reset when I change time-slots in another.

I haven't found something as simple as Calendly -- that just works. A commenter here once commented about a different alternative but that got bought out and shuttered. I'm still on the final look-out till end of this month (FEB), else going back to the Calendly subscription.