How a ticket code is checked
A ticket code usually holds a unique ticket ID rather than the event details. At the door, the scanner looks the ID up in the ticketing system, confirms it is valid for that event, and marks it as used so a copy cannot get in a second time.
Some systems sign the ticket data cryptographically, so a scanner can confirm a ticket is genuine even without a network connection. Duplicate use is then caught when scanners sync their records.
- Unique ID per ticket, never reused
- Checked against the ticketing server, or verified by signature offline
- Marked as used on first entry
- Printed tickets and phone screens both work
Screenshots and rotating codes
A static ticket code can be screenshotted and shared, and whoever arrives first gets in. To deter this, some ticketing platforms show a code that changes every few seconds or is tied to the ticket holder’s phone, so a screenshot stops working.
These rotating codes live inside the ticketing app or a phone wallet pass, and the details differ by provider. Printed tickets cannot rotate, so they rely on the single-use check at the door.
Wallet passes
Apple Wallet and Google Wallet both support event tickets with a barcode on the pass. Supported formats include QR, Aztec, PDF417 and Code 128, and the pass can also show the seat, time and venue.
A wallet pass can be updated after it is issued, for example if the event time changes, which a printed code cannot do.