1. Decode the final file and compare the data

Start with the file you'll actually send to print, not the preview in a design tool. Upload it to thereadability checker. It decodes the image several ways, from full size to blurred and dim, and shows the exact text inside.

Compare that text with what you intended, character by character:

Links: the full URL, including https://, the path and any parameters. A missing slash or a typo in a domain sends people elsewhere.
Wi-Fi: the network name and password, including capital letters and special characters.
Contact cards: phone numbers with country codes, email spelling, and that names land in the right fields.
Redirects: if the decoded link is a short link on someone else's domain, you're relying on that service to keep redirecting. See do QR codes expire?

Codes from our generator show the encoded data above the preview and run this decode automatically, but checking the exported file catches problems introduced later, such as a designer recoloring or cropping the code.

2. Test the destination

A code that scans perfectly can still fail the person scanning it. On a phone, using mobile data rather than your office Wi-Fi:

Does the link open the right page, not a home page or a login screen?
Does it load reasonably fast and read well on a small screen? A desktop PDF menu is hard work on a phone.
For Wi-Fi codes, does the phone join the network? Try both iPhone and Android, since they parse Wi-Fi codes slightly differently.
For contact cards, does the contact save with the right name, number and email?
For events, does the calendar show the right date and time in your time zone?
For review links, does it open the review form for the right business?

3. Print a proof at the final size

Screens are bright, flat and high contrast, so a code that scans from a monitor tells you little about print. Print the whole layout at 100%, not "fit to page", on the real paper or material if you can. Measure the printed code with a ruler and confirm it matches the size you planned. Theprint size guide explains how big each module needs to be.

Look at the proof as a designer would:

Is the quiet zone intact on all four sides, with no text, border or trim eating into it?
Are the edges of the modules crisp, or has the ink spread or the image been scaled up from a small PNG?
On colored stock or with colored ink, is the contrast still strong?

4. Scan with several phones and apps

Camera hardware and decoding software vary a lot. One successful scan on your own phone is a best case. Try:

An iPhone with the built-in Camera app.
An Android phone with its camera app or Google Lens.
At least one third-party scanner app.
An older or cheaper phone, if anyone around you has one. They focus less well at close range.

Pay attention to how fast each one reads the code. If it takes several seconds of hunting, the code is marginal: it'll fail for some people. Make it larger, raise the contrast, shorten the content or reduce the logo, then test again.

5. Test the real lighting, angle and distance

Take the proof to where the code will live, or recreate the conditions:

Lighting. Dim restaurants, bright sun, backlit windows. Glare on glossy laminate or behind glass is a common failure.
Distance. Scan from where people will actually stand, not from 20 cm because it's easy.
Angle. Wall signs are often seen from below or the side. Tilted views squash the code.
Surface. Curved bottles, folded menus and creased flyers distort the grid.
Behavior. Scan quickly, one-handed, without lining things up carefully. That's what most people do.

6. Check that links keep working over time

A static code from our generator never changes and has no account behind it, so the code itself won't stop working. What can break is the destination: a website redesign that moves the menu page, an expired domain, a deleted file share, a closed review profile.

Point codes at addresses you control and intend to keep, like yourdomain.com/menu, rather than a file-sharing link.
If you move a page, add a redirect on your own site from the old address.
Scan a printed copy every few months, and add a reminder to renew your domain.

To check a code someone else made, or one you printed long ago, use the QR code scanner. It shows the raw data without opening the link, so you can see whether the code holds your address directly or a redirect through another service.

A short checklist to keep

Decoded data matches exactly.
Destination works on mobile data, on iPhone and Android.
Printed proof at 100% scale, measured with a ruler.
Quiet zone, contrast and module size look right on the proof.
Scans quickly on at least three devices or apps.
Scans under the real lighting, distance and angle.
Destination is an address you control, with a reminder to check it.