komlan

If you care about reliability, there's no way around scanning the codes yourself (instead of making attendees scan), so you can be sure that each scan maps to an actual attendee, and you're not getting 30 scans from 10 people actually present.

I guess self-check-in became popular in zoom calls during the covid area, but people that need reliability instantly prefer the alternative, when available.

Shameless self-plug: this is precisely why my Google Forms/Sheets check-in plugin is named "Qr code ticket per attendee" [1], because the unique ID per person is what makes it more reliable than self-check-in.

Yes, people can still send friends, but most of the time, you don't care, and it's too much of a hassle for the attendee. People sometimes worry that check-in won't be quick, but QR code reading is very fast [2], and you're only limited by how quick people move.

I used this for digital QR code tickets [2], and it made the codes so much easier to scan, even with bad lighting.

This is very convenient when you control the QR reader and need to represent long numeric identifiers like UUIDs.

For example:

  9728983f-7d7d-4189-b624-f92781e36650 (lowercase UUID):
    => length=36, 15 pixels between markers
  JWM9GFVXFN0RKDH4Z4KR3RV6A0 (base32 UUID):
    => length=26, 11 pixels between markers
  9728983F-7D7D-4189-B624-F92781E36650 (uppercase UUID):
    => length=36, 11 pixels between markers
  200924207194334734815443970355691218512 (decimal UUID):
    => length=39, 7 pixels between markers

The decimal UUID is a longer string, but results in much bigger pixels because it can use numeric encoding.

I have a QR code base attendance tracker [1], where attendees show the code [2] on their phones (glares, etc.), in bad lighting conditions, etc. Bigger pixels means scanning stays quick. Same with parcel tracking [3] where field agents might need to scan QR codes in barely-lit hallways, etc.