Connecting your calendar: how iCal works and where it breaks in practice

What a link does and does not do

An iCal address is a small file that a rental site prepares for you. It states which periods are taken. We fetch it regularly and block those nights in our calendar, so that a guest cannot request a date with us that is already booked elsewhere.

What is NOT in it matters just as much. An iCal file carries no names, no amounts and no contact details. It only says: these nights are gone. Someone who booked on another site therefore stays that site's customer, and you will not see that booking with us.

And it works per direction. A link from Booking to us does not mean a booking with us also closes at Booking. For that you need a second link, the other way round, set up on that other site using the address we give you.

Today 107 of our 222 live properties have such a link. 59 hosts explicitly state they have none and keep their calendar by hand. Those 107 links together produce 21,565 blocked nights, alongside 6,339 nights someone closed themselves.

Which systems we see in practice

The links with us come from ten different systems. That is a wider view than any single host has, and it explains why a problem at one provider looks different from one at another.

The largest groups are MyTourist with twelve links, Huurkalender and Smoobu with eleven each, Elloha with ten, and Airbnb with fifteen once you add the French and Belgian addresses together. Then come Cubilis with seven, Booking with seven, Lodgify with four and Gîtes de Wallonie with four.

That does not spread the risk the way you might think. The problems below are not evenly distributed across those ten: they depend on how a provider builds its address, how long that address stays valid, and whether it rejects an import that looks wrong to it.

What we will not do here is recommend a provider. We connect to all ten and have no stake in which you pick. What we do advise: create the link at your provider itself rather than reusing an address you once copied out of an email. That one may have expired since, without anything showing it.

The five ways a calendar stops

The first is an address that expires. Booking issues an address with a token in it, and that token can become invalid. At one property the Booking address answered with an error message instead of a calendar. The result: her Booking bookings blocked nothing with us, and a guest could request a week that was already taken.

The second is a loop. We also pass your calendar on, so other sites can see our bookings. If you accidentally set that address as a source with yourself, our calendar reads its own output. That happened at one property, and it does not break immediately but drifts slowly.

The third is a provider that suddenly passes far less. At one property the feed dropped to a single entry while 95 nights sat blocked. We held those old blocks rather than clearing them. That is deliberate, because a feed emptied by an outage would otherwise open half a year at once. But it also means a calendar can stay frozen.

The fourth is an address the other site refuses. Airbnb does not accept an address that does not end in dot-ics. Our export link did not in one of its forms, and Airbnb then refuses it without further explanation. The fifth is subtler: for a property let both whole and by the room, one listing can be open while the other is closed, and we follow only one of them.

How you notice it has stopped

The awkward thing about a stopped calendar is that nothing happens. No error message, no email. Your property simply stays online, just with availability that no longer matches. You only notice when someone requests a period that is already taken, and by then the conversation is already difficult.

So we watch it from our side. A check looks at whether each link still delivers work, not merely whether it answers technically, and it raises an alarm as soon as a property sits still too long. That distinction is not theoretical: an address can answer cleanly and still return an empty calendar.

What you can do yourself takes two minutes. Block a random night on the other site and check the next day whether that night is closed with us. Do wait that long: our sync runs roughly every six hours, so after one hour a working link often still looks open. If it is still open, the link is not running. That is a better check than looking at the address, because an address that looks fine may have expired long ago.

And if you are unsure, just ask. We can see from our side when a link last delivered anything and exactly what it returned. That is quicker than searching the settings of a system you perhaps open twice a year.

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