Everest
Everest is aimed squarely at people running more than one calendar at once — a consultant juggling several clients' calendars plus their own — and automates the scheduling negotiation that normally happens over email. It's still in early access with no public pricing, so today's free access is temporary rather than a permanent plan.
Pros
- Works by email thread or direct message, no separate app to learn
- Syncs Google and Outlook calendars without requiring inbox access
- No credit card needed to start using it during early access
Cons
- Still in early access, so pricing and long-term availability aren't settled
- Only supports Google and Outlook, not other calendar providers
- Early-access free pricing will change once the product launches publicly