Answer
How does hotel online check-in connect to the PMS?
Hotel online check-in connects to the PMS through the PMS API: the check-in tool reads the reservation and guest profile, captures ID and payment, then writes the check-in status (and often a room assignment or mobile key) back to the PMS. The integration is only as useful as its write-back, so the question to ask any vendor is whether your exact PMS receives the completed check-in two-way, or whether staff still re-key it.
What online check-in exchanges with the PMS
A check-in integration typically moves five kinds of data between the tool and the PMS: the reservation (dates, rate, room type), the guest profile (name, contact, registration and ID details), the room assignment, the folio (deposit or balance, payment authorisation), and the check-in status itself. Modern platforms exchange this over a REST API with webhooks that fire on reservation and check-in events; older systems still use HTNG or SOAP. The decisive feature is two-way write-back: a completed online check-in should set the guest to checked-in inside the PMS without a staff member retyping anything.
Tools that do check-in and PMS sync live today
Canary runs an app-free contactless check-in that captures ID and payment and syncs the result back to the PMS, including mobile-key delivery; Canary states it is used across 20,000+ hotels in 100+ countries. Duve offers online check-in inside a broader guest-app journey. Each reads the reservation and writes the check-in (and often a key) back, but the exact PMS connector and what it writes differ by vendor and by your PMS.
Where the PMS draws the line, and where Guestivo fits
On API-first systems the check-in event is a first-class webhook. Apaleo exposes reservation-lifecycle events (including check-in and checkout) through its API, and Mews covers reservations, customers, rates, and orders in its Open API, so a check-in tool can subscribe to the event rather than poll. Guestivo sits in this picture as a guest-experience layer that connects on top of the PMS (its only live PMS connector today is Apaleo) for in-stay services; its own online check-in is on the roadmap rather than a live, shipped capability, so a hotel that needs online check-in writing back to the PMS right now should shortlist a live tool such as Canary or Duve.
What to verify in a check-in and PMS integration
The failure pattern is a polished check-in screen that does not actually update the PMS, so the front desk re-keys every arrival and the "contactless" promise collapses at the busiest moment. Verify four things in writing: that your specific PMS is supported today, whether the check-in status writes back two-way, whether the tool also assigns the room or issues a mobile key, and how guest ID and registration data are stored to meet local rules. Ask to see a live check-in against a test reservation in your PMS, not a generic recording.