CalendarPipe

CalendarPipe, indie-built in Prague by Jakub Beneš and Tomáš Růžička, syncs events between Google Calendar, Outlook, and Apple Calendar using customizable rules called 'pipes' that filter, transform, and route events automatically. It offers a visual builder, AI-powered rule generation, or a code editor to create sync rules, invitation-based delivery so recipients don't need accounts or apps, and works behind corporate firewalls. CalendarPipe also provides hosted calendars for AI agents via API, real email invitations for scheduled events, and uses OAuth-only authentication with no password storage. The Free plan includes 2 calendars, 1 rule, and 15-minute sync intervals; Pro is $4/month ($40/year) with unlimited calendars and rules, 5-minute syncing, API access, and AI features, with a 14-day free trial of Pro features (card required, cancellable anytime).