Tool comparison
Kalender Sync vs. Outlook4Gmail – add-in or cloud sync?
Outlook4Gmail is a solid, actively maintained Outlook add-in that syncs Google and Outlook directly on your Windows PC – calendars, contacts and tasks. But it shares the structural limits of all desktop sync tools, and on data protection there's one fact DACH companies should know. Here's an honest look at where Outlook4Gmail is strong and where Kalender Sync makes the difference.
Background
What can Outlook4Gmail do?
Outlook4Gmail is an Outlook add-in by software services company SCAND Ltd., headquartered in Minsk, Belarus. It synchronises Google and Outlook directly on your Windows machine: calendars one-way or two-way, contacts including pictures and groups, and tasks including recurrences. The add-in is actively maintained – the current version 5.6.4 was released in April 2026 – and supports the classic desktop versions Outlook 2003 through 2019 as well as Office 365 on Windows Vista to 11. There's a free basic edition (essentially contact sync), while the full version costs $28.98 one-time per licence including one year of updates and support; a 7-day full-feature trial is available on request.
Strengths
Where Outlook4Gmail is strong
Actively maintained and mature
Version 5.6.4 from April 2026 shows the add-in is continuously developed and supports a wide range of classic Outlook versions. Not an abandoned project, but well-maintained software.
More than calendars: contacts and tasks
Outlook4Gmail also syncs Google contacts including pictures and groups, and tasks including recurrences. If you want to mirror your entire Google data set in classic Outlook, you get more than pure calendar sync here.
Local instead of third-party servers
The add-in runs on your PC and talks directly to Google – no additional cloud service sits permanently between your calendars. If you don't want another processor in the chain, that's an honest privacy plus.
A free edition and an affordable one-time purchase
The basic edition is free, the full version costs $28.98 one-time instead of a subscription – with a 15-day money-back guarantee. A fair deal for individual users.
Where Kalender Sync wins
Where Kalender Sync wins
GDPR assessment: vendor in Belarus vs. a German contractual partner
Developer SCAND is based in Minsk, Belarus – outside the EU and without an adequacy decision. That's no accusation against the product, but a fact for the compliance assessment: for DACH companies that must classify support access, updates and contractual relationships in a GDPR-clean way, it's hard to evaluate. Kalender Sync is run by PPJ Venture Labs UG in Munich, hosts at Hetzner in Nuremberg and offers a DPA – German contractual partner, German law, German-language support.
Future-proof despite New Outlook
Outlook4Gmail is a classic add-in for the desktop versions Outlook 2003 through 2019/365. But Microsoft is gradually replacing classic Outlook with the „New Outlook", which no longer supports local COM add-ins. Kalender Sync works cloud-side directly with the calendar servers – which client you use doesn't matter to the sync.
Sync runs 24/7 – not only while the PC is on
Outlook4Gmail synchronises as long as your Windows machine is running Outlook. PC off or laptop closed? Then the sync stops – and exactly in that window double-bookings happen. Kalender Sync runs on our servers around the clock; your double-booking protection has no gap.
Device-independent instead of one sync node
With Outlook4Gmail, a Windows PC running classic Outlook is the sync node – no Mac, no mobile-only setup. You set up Kalender Sync once in the browser (about 2 minutes), and from then on every device benefits automatically: Windows, Mac, iPhone, Android, web.
Genuine live-sharing into other calendars – with two-way sync
Outlook4Gmail syncs your own accounts. Kalender Sync not only synchronises bidirectionally between your own calendars, it can also embed your availability into another person's calendar by invitation – as real events, no fragile ICS subscription. They accept once, and from then on everything stays synced automatically.
Three visibility levels per sync – with custom display names
You decide per synchronisation whether only „Busy", „Title + time" or full details are transferred – and you set the name a blocked slot shows up as on the other side. Fine-grained control designed for sharing with third parties.
A free plan without stripped-down calendar sync
One full-featured synchronisation is permanently free with Kalender Sync – no credit card. Beyond that: Basic at €4/month, Business at €10/month. You can try all features free for 14 days.
Decision guide
When should you pick which?
Outlook4Gmail is the right choice if:
- You use classic Outlook on Windows and are staying there.
- You want to mirror Google contacts and tasks in Outlook, not just calendars.
- You deliberately don't want a cloud service between your calendars.
- An affordable one-time purchase is enough for you and the vendor's location isn't a compliance concern.
Kalender Sync is the right choice if:
- You need a vendor you can classify cleanly under GDPR: German company, Hetzner hosting, DPA.
- Your sync should keep running when the PC is off – double-booking protection without a time-window gap.
- You use Mac, iPhone, Android or New Outlook – or will in the future.
- You want to share your availability live into other people's calendars – with three selectable visibility levels.
- You want the broadest provider coverage in this comparison: 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.
Ready for calendar sync with a German contractual partner and a DPA?
Connect your calendars in about 2 minutes in the browser – cloud-side around the clock, GDPR-compliant and hosted in Germany, with genuine live-sharing. The free plan stays free forever.
Try free for 14 daysCurrently supported providers
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