There is an open source for Acuity Scheduling

"EasyAppointments (https://github.com/alextselegidis/easyappointments) is still FOSS. We managed our team calendars on it at a previous company, but I rolled out Cal.com due to more apparent support and sophistication at my current company. Turns out most of that sophistication turned out to be bloat: we saw successive version releases add features we didn't care about while increasingly putting previously open features, like team calendars, behind a paywall. This move by Cal.com seems to be transparently an attempt to maintain that paywall against users who'd otherwise just use LLMs to remove it. I guess it's back to EasyAppointments, which still seems to work just fine."