Caltsu and Cal.com compared
Cal.com reads your connected calendars so its booking pages only offer free times. It does not write blocks into your other calendars. A colleague booking you directly in Outlook still sees a free slot where your other calendar is busy. Caltsu covers that side, and the two can run side by side.
- Main job
- CaltsuCalendar syncCal.comBooking pages and scheduling
- What the other calendar receives
- CaltsuA block with the start and end time, the title Busy or your own text, and a note naming the source calendar. Never the event title, attendees, location, notes or meeting link.Cal.comNothing. Busy times are checked only for Cal.com bookings.
- Google Calendar
- CaltsuYesCal.comYes
- Microsoft 365 and Outlook
- CaltsuYesCal.comYes
- Apple iCloud
- CaltsuNot yetCal.comYes
- Open source and self-hosting
- CaltsuNoCal.comYes
- Price
- Caltsu€5 per month or €48 per year. One plan, 14-day trial without a card.Cal.comFree for one person. Team plans from $12 per user per month.
- Database location
- CaltsuPostgreSQL in Frankfurt, GermanyCal.comTheir cloud, or your own server if you self-host
| Topic | Caltsu | Cal.com |
|---|---|---|
| Main job | Calendar sync | Booking pages and scheduling |
| What the other calendar receives | A block with the start and end time, the title Busy or your own text, and a note naming the source calendar. Never the event title, attendees, location, notes or meeting link. | Nothing. Busy times are checked only for Cal.com bookings. |
| Google Calendar | Yes | Yes |
| Microsoft 365 and Outlook | Yes | Yes |
| Apple iCloud | Not yet | Yes |
| Open source and self-hosting | No | Yes |
| Price | €5 per month or €48 per year. One plan, 14-day trial without a card. | Free for one person. Team plans from $12 per user per month. |
| Database location | PostgreSQL in Frankfurt, Germany | Their cloud, or your own server if you self-host |
Cal.com details come from its public website, checked September 2026. Plans change, so confirm on their site before you decide.
When Cal.com fits better
- People outside your organization book time with you through a link.
- You want to read the source code or run it on your own servers.
When Caltsu fits better
- Colleagues and clients book you directly in their own calendar, not through a link.
- Each of your calendars should show the time you are busy in the others.
Running Cal.com and Caltsu together
Cal.com hides times that are busy in the calendar it checks. Caltsu makes that calendar busy whenever any of your other calendars is. With both, a booking link and a colleague booking you in Outlook see the same availability.
Bookings made through Cal.com land in its destination calendar, and Caltsu copies them to your other calendars as Busy blocks.
Personal Google calendar
Has a dentist appointment on Tuesday at 08:30.
Caltsu
Writes a Busy block for 08:30 to 09:15 into your work calendar.
Work Microsoft 365 calendar
Shows you as busy to colleagues who book you directly.
Busy08:30-09:15Cal.com
Reads the work calendar and leaves 08:30 off your booking page.
Try it on your own calendars.
Other comparisons: OneCal, CalendarBridge, Reclaim.ai, Clockwise