Events: slides, badges and check-in without a tracker

What to put in the code

Schedule and feedback are URLs — encode them on the homepage. Prefer a short, stable https link you control. UTM parameters make the matrix denser and do not help you if you are not reading analytics anyway. Speaker contact is a vCard: name, title, one phone or email, maybe a site. Do not dump every social handle into the card if the preview already looks speckled.

Why static is a feature here

Organisers are often pushed toward “dynamic QR” so they can see how many people scanned the slide. That count is a redirect through a vendor. For a local talk, the cost is an extra failure mode: the vendor is down, the short link expired, the slide is a dead square. A static code printed in the PDF of the slides still works next year if the URL still works.

If you genuinely need attendance numbers, collect them at the form the code points to, on a site you operate — not in the QR layer.

On a projector

Projected codes fight with keystone, brightness and people in the aisle. Make the mark large, high contrast, no logo, and leave it up for more than one second. A handout or a table tent is more reliable than the last slide of a lightning talk.

Badges

A vCard on a badge saves typing. It also publishes a phone number to anyone with a camera. Ask speakers before you print their mobile. Mark does not keep a copy after the tab closes; the badge is the copy.