We do not currently offer a way to "check in" an attendee or barcode over the api. You can check for a valid order number however, by sending a request and seeing if the response is an http 200.
- /v3/events/:id/orders/:id/ -> check for valid order
*Note the order number is included in the conformation email the attendee receives, as well as, the PDF printed ticket. However, there is not a way to extract the order number from the QR code.
Cheers,
Nathan