Two guests, one apartment, the same night. A double booking is every host's nightmare — and it almost always arises the same way: the calendars on the individual platforms know nothing about each other. The solution has four letters: iCal. It is free, most of the big platforms and the larger Czech portals can do it — but not all of them and not under all conditions. And the basic link is just a matter of copying and pasting two addresses.

One thing has to be said right at the start, though, because everything else follows from it: iCal is not instant. Airbnb reads other calendars every 3 hours, Booking.com every 2 hours, some Czech portals only once a day. Booking.com says so openly in its partner help — calendar synchronisation does not happen in real time. For most hosts iCal is enough and cuts the risk to a fraction; full real-time protection is given only by a full connection via API. → Channel manager: when iCal stops being enough

What to do

What iCal is and what it actually transfers

The format is properly called iCalendar and is described by the RFC 5545 standard (IETF, September 2009); the files have the .ics extension and the abbreviation „iCal" is established even with the platforms themselves. In practice it is a plain text file at a secret address at which the platform continuously publishes the occupied dates. Anyone with that address can download them regularly — and that is exactly what the platforms do with each other.

The link is always a PAIR of addresses: the export from A pasted into B and the export from B pasted into A. Whoever sets up only one direction protects only one side.

What iCal transfers: dates from–to and a short text for the event. Nothing more. Since 1. 12. 2019 Airbnb has not stated the guest's name or the booking code in the export — the event is called „Reserved" and the description contains only the fields „Reservation URL" (a link to the booking detail) and „Phone Number (Last 4 Digits)", that is the last four digits of the phone number. Booking.com sends technical texts such as „CLOSED – Not available". The name and order details are transferred from the usual channels practically only by e-chalupy.cz in the „including details" export variant.

What iCal does not transfer: guest contacts, prices, numbers of people, services, messages. For that a full platform connection via API or a connectivity provider is needed.

Where to find the links

AIRBNB. Calendar → choose the listing's calendar → Availability → in the „Connect calendars" section click „Connect to another website". One dialogue holds both: the Airbnb link to copy (export) and the field into which you paste the other .ics address, name it and confirm with the „Add calendar" button (import). The older names „Calendar sync", „Export calendar" and „Import calendar", which you will find in most guides on the internet, belong to the previous interface.

BOOKING.COM. „Rates & Availability" → „Sync calendars" → at the given unit „Add calendar connection" → paste the other link → name the connection (say „Airbnb") → „Next step" → „Done". The export is offered in the same wizard. We give the English names because Booking.com's official partner help is in English only — in an extranet switched to another language look for the labels above. Two extra things: with the export you choose whether to send only bookings, or bookings and closed days as well — choose bookings only, so that you do not push your operational blocks to the other portal. And Booking.com shows the state of each connection as Activating, Okay, Import only, Export only or Service error; „Activating" means the connection is still being switched on, „Okay" that it is running both ways — „Import only", „Export only" and „Service error" signal that one direction or the whole connection is not working.

CZECH PORTALS:

• e-chalupy.cz — Occupancy → Calendar synchronisation → EXPORT → the green „Copy link" button; the import at Occupancy → Calendar synchronisation → Import. e-chalupy.cz has calendar synchronisation only in the top tariff.
• megaubytko.cz — Occupancy calendar → „Synchronise the calendar with another portal" → the „Calendar export" tab → „Copy link", or „Calendar import" → name it → „Paste the link".
• chatalevne.cz — in the administration: edit the property → the „Occupancy calendar" tab → the „iCal Export" button (copy the link), or „iCal Import" / „Add external calendar". The portal can accept several calendars at once; it has a guide to this on its public website in the owners' section.
• chata.cz and pampeliska.cz — there is no self-service import in the administration. The connection is set up by the portal: write to zubalik@chata.cz and state the property number and the name of the system you are sending the calendar from. The link at the same time activates the „Guaranteed occupancy" cooperation.
• Hotely.cz (formerly hotel.cz and penzion.cz) — both brands were merged, together with spa.cz, under Hotely.cz operated by the Szallas Group as of 1. 7. 2025, and the administration runs at admin.hotely.cz. Even after the merger iCal is set up through support (podpora@hotel.cz). Beware: since March 2025 errors have been appearing with this feed — the original event identifiers change, anonymous foreign records of the „Szallasz.hu (Not Available)" type come through and a booking cannot be told apart from a mere block. Before you rely on it, check by hand for a few days what actually arrives from it.

→ Czech portals for cottages and cabins: where to list and how to link calendars

The right set-up with our app

The simplest architecture is the app as the HUB. Instead of linking every channel with every other one (with four channels that is twelve links), you run everything through one place.

1. 1You paste the export links of all the platforms and portals into the app — at the apartment → iCal calendars. Bookings are downloaded automatically every 5 minutes and you see them in a single calendar; any overlaps we report at once.
2. 2From the app you take our occupancy export link (again at the apartment) and paste it into the platforms and portals. That way the occupancy from manual bookings and from channels that are not directly linked to each other reaches them too.
3. 3You check the shape of each link: it starts with http:// or https:// and ends with .ics. A link to an ordinary portal page does not work, even if the word „calendar" is in the address.

The result: every channel knows about all the others and you have a single source of truth.

The most important limit: time

Platforms read other calendars at intervals, not continuously. Usually it is 2–3 hours — Airbnb updates automatically every 3 hours according to its help, Booking.com imports connected calendars every 2 hours — and with some portals it is up to 24 hours. A clash can arise in that window: two guests „manage" to take the same night on two platforms before the calendars learn of each other.

The window can be shortened by hand. Booking.com has an „Import now" button with every connection, which loads the other calendar immediately — and integrators warn from practice that the automatic import on Booking does not always run reliably and a manual click is the sure thing. Airbnb has a similar „Refresh" button, but with a limited number of requests; once they are used up you must wait for the next automatic update.

The practical conclusion: for dates within 72 hours from today do not rely on automation.

How to cut the risk to a minimum:

• link ALL channels — the most common double booking comes from a channel that „did not count": an enquiry portal, a manual booking over the phone, a booking from friends,
• enter manual bookings in the app at once, the export will carry them further,
• with last-minute offers reckon with the delay — leave a day's buffer, or confirm enquiries manually,
• before confirming a near date on a portal with a slow import, click the manual refresh,
• watch our overlap warnings: when a clash arises, speed decides — one of the bookings must be sorted out with the guest as soon as possible.

The most common mistakes and myths

• „I have Airbnb linked with Booking, I am safe." — As long as the last channel stays outside (an enquiry portal, a phone call, a friend), the risk remains. Only a complete set of links protects you.
• „Export and import are one and the same." — They are not. Swapping them means pasting your own export „into yourself"; the calendar looks as though it works and transfers nothing.
• „The link is long and nobody will guess it, I can send it to the cleaner in a group chat." — The link is not password protected and carries personal data: with Airbnb the last four digits of the guest's phone number and a link to the booking detail, with e-chalupy in the „including details" variant the name and order data as well. These are personal data within the meaning of the GDPR, so they belong only in the system that processes them. If the link does leak after all, have the platform generate it again, remove the old connection (on Booking.com with the „Remove" button) and set up a new one — and then rewrite the new link everywhere you pasted the old one, otherwise the calendar there quietly freezes. → GDPR and guest data: what you may, what you must and what is forbidden
• „With e-chalupy it does not matter which export variant I choose." — It does. The variant without details changes the identifiers of foreign, imported bookings and passes them off as its own; the receiving system then loads them as new ones and false, duplicate bookings arise.
• „I changed the link on the platform, but here it is still the old one — it will sort itself out." — It will not. The old link stops returning data and the calendar quietly freezes on the last download.
• „iCal will transfer names and prices for me, I do not have to rewrite anything." — It will not. The dates and a few technical fields, nothing more. Complete data goes only through an API.

Frequently asked questions

Updated: 5. 9. 2026, verified against the sources listed. Informational text, not legal or tax advice — discuss your specific situation with a professional.