Both iCal and an API connection can keep calendars in sync, but they are not in the same league. The choice has a direct impact on your double-booking risk and on the time you spend updating prices across channels.
The short answer
iCal only exchanges calendar events (blocked dates), at a pace set by each platform. An API connection syncs much more: reservations with their details, availability, rates, restrictions and sometimes messages. For a professional operation on several channels, use an API connection for the major platforms and keep iCal for secondary channels.
What iCal does
The iCalendar format has been a standard for a long time. Each platform publishes a calendar link that the others read at regular intervals. It is simple and widely supported, but it has clear limits:
- the refresh rate depends on the platform reading the link, and can be several hours;
- only dates travel: no price, no minimum stay, no guest name, no amount;
- a change or cancellation is only picked up at the next read.
What an API connection does
An official API gives your software a richer, faster connection to the platform. Booking.com, for example, documents APIs that let connectivity partners manage availability, rates, reservations and content. Reservations arrive with their details, and the prices and restrictions you set in your software are pushed to the platform.
| iCal | API connection | |
|---|---|---|
| Data exchanged | Blocked dates | Reservations, availability, rates, restrictions |
| Speed | Depends on each platform's polling interval | Updates pushed on every change |
| Prices and minimum stay | No | Yes, depending on the integration |
| Setup | Copy and paste a link | Authorize the software from your platform account |
| Best for | Secondary channels, low volume | Major platforms, Instant Book |
Why you still need both
A good property management system (PMS) uses the API for the main channels and keeps iCal for the rest. That is how Boostinghost works: Airbnb, Booking.com, Vrbo and Expedia are connected through the API, while any other iCal-compatible platform syncs through calendar import and export.
How to choose
If you rent one property occasionally on two sites, iCal may be enough. If you manage several listings with Instant Book and prices that change often, go with an API connection. Either way, never leave an old iCal link active once a channel is connected through the API.
Frequently asked questions
Does iCal prevent all double bookings?
No. It reduces the risk, but between two calendar reads the same night can be booked on two platforms. The longer the interval and the higher the demand, the higher the risk.
Can I use the API and iCal at the same time?
Yes, on different channels: API for the major platforms, iCal for the others. Do not use both for the same channel and the same listing.
Is an API connection always better?
It carries more data, faster, but its quality depends on the integration: listing mapping, handling of changes and cancellations, and how restrictions are pushed. Test with real bookings.
How do I know whether my software uses the API or iCal?
An API connection is set up by authorizing the software from your platform account; an iCal connection means copying a calendar link. Ask your vendor which method is used for each channel.
Key takeaways
Use an API connection for Airbnb, Booking.com, Vrbo and Expedia, and keep iCal for secondary channels. One tool should own the calendar, and no old iCal link should stay active on a channel connected through the API.
Sources
- https://developers.booking.com/connectivity/docs
- https://datatracker.ietf.org/doc/html/rfc5545
- https://news.airbnb.com/announcing-our-2025-preferred-software-partners/
