How long does the offline copy stay valid?

For the whole event. Door staff links stay valid until you remove the staff member, so a phone can go offline for hours.

What if a phone dies before it syncs?

The queue is on that phone. Charge it, open the scanner and it syncs. Only a lost phone loses its unsynced check-ins; other devices are unaffected.

Can I check in guests who registered after the list was downloaded?

Only after a sync. If you expect late registrations, keep at least one device online, or refresh the list when you have signal.

Does the scanner work without internet, and how does syncing work?

Short answer

Yes. When the scanner opens with a connection it stores the full guest list on the phone. If the connection drops, scanning and name search keep working from that copy; each check-in is queued and marked on the device. As soon as the phone is back online, the queue syncs automatically and the other devices and your dashboard update. Nothing is lost when the phone locks or the browser closes.

Before the doors open

Open the scanner on every device while you still have Wi-Fi or mobile data. The guest list downloads in the background.
Check that the guest count on the dashboard matches your list. Guests added later are picked up on the next sync.
Do not sign out or clear the browser; the local copy lives in the browser.

While offline

Scanning shows the same green, yellow and red results, from the local copy.
Each check-in is saved on the device and shows "queued, will sync".
Two devices offline at once cannot see each other's check-ins until they sync. A guest scanned at door A could pass door B in the meantime; with a connection this is caught within seconds.

Back online

Queued check-ins upload automatically, including the original scan time and who scanned.
Duplicates are merged: if the same guest was scanned on two offline devices, you see one check-in with the earliest time.
The dashboard and all other devices refresh.

Real-time when online

With a connection every check-in is written at once and pushed to all devices and the organizer dashboard. Adding a guest in your account makes them scannable within seconds.

Questions about this

How long does the offline copy stay valid?: For the whole event. Door staff links stay valid until you remove the staff member, so a phone can go offline for hours.
What if a phone dies before it syncs?: The queue is on that phone. Charge it, open the scanner and it syncs. Only a lost phone loses its unsynced check-ins; other devices are unaffected.
Can I check in guests who registered after the list was downloaded?: Only after a sync. If you expect late registrations, keep at least one device online, or refresh the list when you have signal.