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.
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.
What Calendly doesn't solve – and Kalender Sync does
Tap a point to see the reasoning.
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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.
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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.
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Providers Calendly doesn't even know
Calendly connects Google, Microsoft and friends – but no GMX or WEB.DE calendar. Kalender Sync connects 10 provider types directly and brings their events to where your booking tool actually looks.
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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".
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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.
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A GDPR foundation under the US booking tool
Calendly is a US provider. Kalender Sync is GDPR- and BDSG-compliant, hosts at Hetzner in Germany and offers a DPA on every plan for business use. The sync layer that moves your private events stays fully under European law – and all Calendly ever sees is "Busy".
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Costs less than a Calendly upgrade
One sharing is permanently free, Basic costs €5/month (3 accounts), Professional €12/month (unlimited) – with a 7-day Professional trial, no credit card. The add-on layer for your booking setup costs less than most booking plans themselves.
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: 10 provider types – Google, Microsoft Outlook/M365, Apple iCloud, GMX, WEB.DE, mailbox.org, Posteo, STRATO, Infomaniak kSuite and iCal feeds. Kalender Sync is the only tool in this comparison with ready-made connections for the German providers GMX & WEB.DE – no server address to type in.
- 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 7 daysCurrently supported providers
GoogleMicrosoftApple iCloudKSuiteGMXWEB.DEmailbox.orgiCal-Feeds