CalendarPipe syncs Google, Outlook and Apple calendars with rules that filter and rewrite events. Free plan available; Pro is $4/month.
Researched and fact-checked by Bartu Cavusoglu · Updated October 26, 2026
CalendarPipe is a programmable calendar sync service that connects Google Calendar, Microsoft Outlook, and Apple Calendar through rules called pipes. A pipe decides which events move from one calendar to another and how they look on arrival, so a private appointment can block work time without exposing its title, notes, or location.
The product is built by two engineers in Prague, Czech Republic. Beyond sync, the same rules drive booking pages that decide which events count as busy, and a hosted calendar API gives AI agents a calendar of their own.
You connect two calendars, then write a rule. The rule is a small function that runs on every event and decides whether to block it, let it through, or rewrite it first. You can build it in a visual builder, describe it in plain English for AI to generate, start from a template, or write TypeScript. All four modes produce the same pipe.
Events are fetched, run through your rules, delivered to the target, and discarded. Synced events are tracked, so reschedules and cancellations follow the original. Delivery can use a normal calendar connection or a standard email invitation, which suits work calendars where IT blocks third-party OAuth.
The core feature is the pipe, which can filter by fields such as busy status, response status, or start hour, and transform titles, descriptions, and locations. Templates cover common cases, such as syncing only evening events or showing every event as Busy. One rule moves events in one direction, so mirroring both ways takes two rules.
Other capabilities include booking pages, where visitors see only free time and receive a real invitation, and invitation-based delivery capped at 30 days. Developers get a REST API, webhooks, and Agentic Hosted Calendars, while the security model relies on OAuth tokens, AES-256-GCM encryption, and sandboxed pipe code.
CalendarPipe is a programmable calendar sync service. It connects Google Calendar, Outlook, and Apple Calendar through pipes, rules that filter, transform, and route events between them. The same rules also decide what counts as busy on its booking pages.
The Free plan costs nothing and has no expiry. Pro costs $4/month or $40 billed annually, and Business is custom-priced through the sales contact. The company states that there is no per-calendar or per-seat pricing.
Yes. Pro includes a 14-day free trial with full feature access. A card is required at signup but is not charged until day 14, and canceling returns you to the free plan.
It supports Google Calendar, Microsoft Outlook (including Office 365 and Outlook.com), Apple Calendar over CalDAV, and ICS feeds. Invitation delivery can also reach other calendars through standard email invitations.
Events are fetched, run through your rules, and delivered without being stored; the only stored events are those on hosted calendars. Access uses OAuth, tokens are encrypted with AES-256-GCM, and pipes run in a sandbox with no network access.
Yes, on Pro. Invitation-based delivery sends events as standard email invitations, so no OAuth connection or IT approval is needed. The recipient accepts the invite and the event appears in their calendar.
Yes. A booking page gives you a link that shows only your free time, and visitors get a real calendar invitation by email without an account. Free includes one booking page reading one calendar, while Pro offers unlimited booking pages.
Yes. Pro includes a REST API, Agentic Hosted Calendars, webhooks, and installable agent skills for tools like Claude and Cursor. An agent can create its own calendar, add events, and send invitations by email.