Calendar Sync mirrors events between your calendars and rewrites the title to "Busy" on the way over. Free, no signup to try it.

If you have a work calendar on Google and a personal one on Outlook (or any combo), they don't know about each other. Coworker books you 4 PM Monday, you accept, now you're double-booked with a therapist appointment that lives elsewhere. The fix nobody bothers with is the one that works: a one-way sync that mirrors your busy time without leaking details. Calendar Sync does that.

What people actually build with it

Six patterns account for nearly everything people set up:

• Privacy masking — the most common by a wide margin. A private event on your personal calendar lands on the work one as "Busy," with the title, description, location, and guest list left behind.
• Two accounts that have never heard of each other — a work account and a personal one, or two clients who each gave you a login. Add an event in one, watch availability update in the other.
• Bridging different providers — your company is on Outlook, your life is on Google. Same setup as above; the provider mix just isn't the part that matters.
• Feeding a shared calendar — push matching events onto a team or family calendar automatically, instead of remembering to double-enter them.
• One master calendar — several sources collapsing into a single place you actually look at.
• Selective syncing — copy only the events that match, and transform their titles on the way. Client meetings go over; everything else stays put.

Underneath all six is the same shape: work/personal boundary management, and not getting double-booked by a calendar that can't see the other one. Worth calling out one move that isn't obvious — copying events across as Free. The event shows up for reference, but it doesn't block your availability. People use it constantly.

How it works

Pick a source calendar (real titles) and a destination (the one coworkers see). Calendar Sync watches the source for new, updated, or deleted events and copies them over. Source is never modified.

The interesting part is the rule layer. Before each event copies, you decide what to keep and what to strip:

• Title — keep, replace with "Busy," or use a template like [Personal] {original_title}.
• Description, Location, Attendees — keep, blank, or override.
• Show as — Busy, Free, or Tentative regardless of how the source is marked.

Conditions are arbitrary: visibility, attendee count, day of week, duration, organizer email, location, all-day vs. timed. "If visibility = private, copy as 'Busy' with attendees stripped" — everything else mirrors through unchanged.

What the destination calendar ends up looking like

Toggle between the two views. Same week, two rules running: private events collapse to "Busy," work meetings keep their real titles.

Nobody on the work calendar learns about therapy or the recruiter lunch. The renewal call still reads as the renewal call, because there was never a reason to hide it.

The presets are starting points, not the ceiling

The tool opens with four one-click rules — mask private events as "Busy," mask everything, strip attendees only, show copies as Free. They're there so you have something on screen in two seconds, not because they're where most people stop.

The rule builder underneath them is the actual product. Stack as many conditions as you want, match on all or any of them, and set each field on the copy independently:

• Match on anything the event carries — title, description, location, organizer, duration, attendee count, hour of day, day of week, weekday vs. weekend, all-day vs. timed, visibility.
• Rewrite each field separately — title (literally, or templated with {original_title}), description, location, attendees kept or stripped, and Busy/Free/Tentative independent of the source.
• Decide what happens to everything else — non-matching events either don't copy at all or mirror through untouched.

That combination gets specific fast, which is where the real setups live. Selective syncing is a rule that only copies events whose organizer is a particular client. The Free trick is a rule that copies your partner's travel onto your work calendar as visible-but-not-blocking. A shared family calendar is a rule that forwards weekend and all-day events and ignores the rest. None of those are presets — they're four clicks past one.

Start from a preset, then edit it until it matches how you actually work. The preview re-runs on every change, so you can see exactly what leaks before you connect a calendar.

Why not just share a calendar

Native sharing is all-or-nothing. Either coworkers see everything or they don't. Free/busy permissions exist but leak edge cases nobody trusts. A separate sync layer flips the model: produce a sanitized copy on the calendar people already have access to. They see one calendar — the work one — and it's already accurate.

Calendar Sync is free and runs alongside the rest of Carly's free tools — group polls, booking pages, and the MCP server. No paid account required.

Try Calendar Sync →