Wedding invitation QR code: 5 checks before you send

It's 11pm and you drop the wedding invitation QR code into the WhatsApp group. Two minutes later your aunt replies: 'It won't open.' On your screen the code is sharp and centred. On hers, nothing happens. The invitation itself is fine. The way you tested it wasn't.

A wedding invitation QR code is only tested once it has opened on phones that aren't yours. Five checks, about ten minutes of work, and you'll know it holds up before the first guest tries to reply.

A wedding invitation QR code needs three phones, not one

Your own phone is the worst place to test it. You know which way to tilt it and your screen is clean. Open the code on an older Android, on a phone with a cracked screen, and on the phone of someone who uses large text and holds it at arm's length. If one of the three fails, the code isn't ready yet.

• Open the QR on three phones: yours, an Android that is five years old, and the phone of someone over 70.
• Scan it twice, once with the native camera and once with a separate QR reader app. Cameras handle light backgrounds and low contrast differently.
• Hand the phone to someone and say nothing. If they ask where to tap, the problem is your wording, not the code.
• Try scanning while walking, at arm's length, the way people actually do it, instead of the careful way you do it at your desk.

The terrace test: brightness, distance and background

Turn your screen brightness down to 30% and scan from 30 cm away, as if you were at a dinner outside at night. If the code only reads at full brightness, it will fail on half the phones at the party.

Then place it on a white tablecloth and on a dark wooden table. A QR code needs a quiet margin around it and contrast between the code and whatever sits behind it. Put one on patterned linen or over a photo and it disappears.

A QR code is a door, not the only way in. Send the link next to it and nobody ends up standing outside.

Change the time later and the same QR should still open

Move dinner from 8pm to 9pm after you've sent everything, then scan the same code again. It should open the updated version, not an old copy. If you saved the QR as an image or forwarded it to a group, check that it still points to the same page, because your guest sees the change the moment you make it. Do the same with the RSVP form: edit one question and confirm it still submits from the code. And before the QR reaches the full guest list, send it to one person with a single line of text, the link, the code and the reply deadline. If they write back 'it won't open', you still have time to fix it. If you would rather the code wasn't the only point of failure, a Send The Joy invitation is shared by link and by QR, you can edit it after sending without resending anything, and guests reply from their browser. Try the cover for free and publish once all five checks come back green.