Tool comparison
Kalender Sync vs. Calendly – why you probably need both
Let's be upfront: Calendly is not a competitor to Kalender Sync. Calendly is a booking tool, Kalender Sync is a sync tool – and the two complement each other almost perfectly. The catch with Calendly alone: it only checks your availability in the calendars you've connected. Everything else – your private GMX calendar, iCloud, the tenant of your second company – is invisible to your booking page. That's exactly where Kalender Sync comes in.
Background
What can Calendly do?
Calendly is the market leader for appointment booking: you share a link, the other person picks a free slot, the meeting lands in the calendar automatically – complete with reminders, Zoom/Teams links and team features like round-robin. The free plan is permanently free but allows only 1 calendar connection per user. Paid plans (Standard from $10, Teams from $16 per user/month billed annually, Enterprise from $15,000/year) raise that to up to 6 calendar connections. The crucial point for this comparison: Calendly checks for conflicts exclusively in the connected calendars – anything not in there counts as free and gets offered up for booking.
Strengths
Where Calendly is strong
The standard for booking links
"Send me your Calendly" has become everyday language. Booking pages, event types, buffers, reminders, no-show reduction – as a booking tool, Calendly is as mature as it gets.
Team scheduling and integrations
Round-robin, collective scheduling, CRM connections, automatic video links: for sales and recruiting teams, the workflow package is the real reason to buy.
Permanently free entry point
The free plan covers one event type with one connected calendar – enough for many solo users to be professionally bookable.
Where Kalender Sync wins
What Calendly doesn't solve – and Kalender Sync does
Calendly only sees what's connected
Booking tools check availability exclusively in the connected calendars. Your private GMX calendar, the iCloud family calendar, the M365 tenant of your second client – if they aren't connected (or aren't allowed to be), your booking page offers slots you've long since filled. The result: double bookings. Kalender Sync mirrors all those events as "Busy" into exactly the calendar Calendly checks – and the problem is solved structurally.
The free-plan lever: 1 calendar connection is suddenly enough
Calendly's free plan allows exactly 1 calendar connection. Instead of upgrading to Standard just to connect more calendars, let Kalender Sync mirror all your other calendars into that one. Calendly sees the full truth – on the free plan.
Providers Calendly doesn't even know
Calendly connects Google, Microsoft and friends – but no GMX or WEB.DE calendar. Kalender Sync connects 9 provider types and brings their events to where your booking tool actually looks.
Three visibility levels – private stays private
You decide per sync what arrives in the target calendar: "Busy" only, "Title + time" or full details – even with a custom display name for blocked slots. Your work calendar gets reliably blocked without it saying "couples therapy".
Two-way sync and live-sharing – more than booking
Kalender Sync synchronises in both directions and can embed your availability into another person's calendar by invitation – as real events, not an ICS subscription. That solves the cases where a booking link is the wrong tool: colleagues, assistants, long-term clients.
A GDPR foundation under the US booking tool
Calendly is a US provider. Kalender Sync is GDPR- and BDSG-compliant, hosts at Hetzner in Nuremberg and offers a DPA for business customers. The sync layer that moves your private events stays fully under European law – and all Calendly ever sees is "Busy".
Costs less than a Calendly upgrade
One synchronisation is permanently free, Basic costs €4/month (5 accounts), Business €10/month (unlimited) – with a 14-day Business trial, no credit card. The add-on layer for your booking setup costs less than most booking plans themselves.
Decision guide
When should you pick which?
You use Calendly (and keep it) if:
- You need booking links – strangers should book time with you on their own.
- You want team features like round-robin, workflows and CRM connections.
- Your entire scheduling world lives in the calendars Calendly has connected.
Kalender Sync joins the stack if:
- Your booking page offers slots you've long since filled – because private or external calendars are invisible to Calendly.
- You want to stay on Calendly's free plan even though you have more than one calendar.
- You need calendars Calendly doesn't connect: 9 provider types – Google, Microsoft Outlook/M365, Apple iCloud, GMX, WEB.DE, mailbox.org, Infomaniak kSuite, CalDAV and iCal feeds. Kalender Sync is the only tool in this comparison that connects the German providers GMX & WEB.DE.
- Private events should only ever show up as "Busy" – with visibility you choose per sync.
- You additionally want to share availability live with specific people, not just via a booking link.
Keep Calendly – just finally give it all your calendars
Kalender Sync mirrors every one of your calendars as "Busy" to where your booking tool looks. GDPR-compliant, hosted in Germany, from €0.
Try free for 14 daysCurrently supported providers
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