Calendly

Calendly publishes the times you are genuinely free and lets somebody claim one, which settles in a click what usually takes three emails. Buffers, round robin and paid bookings are there when the calls start earning. The free plan allows one event type, so anybody running a coaching call and a sponsor call from the same calendar pays.

The free plan connects one calendar and publishes one event type. Standard is $10 a seat a month and adds unlimited event types, the integrations and the API. Teams is $16 and adds round robin and routing. Enterprise starts at $15,000 a year. Every one of those prices is quoted billed yearly with no monthly figure beside it, so budget on the annual number. At the end of the 14-day trial the account drops to the free tier rather than being charged.

Anybody who sells their time or has to give it away to sponsors: coaches, consultants, freelancers taking discovery calls. The free plan allows one event type, so two kinds of call at two lengths makes this a paid tool.