1. What Actually Happens
A QR code scanned with a [QR scanner](/qr-scanner) holds text. Scanning produces a link. Installing an app from a non-store source requires you to download an APK and allow installs from that source, which Android asks you to enable per app.
2. Warning Prompts
* A page urging you to "update" an app by downloading a file.
* A prompt to enable installs from unknown sources for your browser.
* A request for accessibility service access or device administrator rights.
3. Safe Practice
Install apps only from the official store, keep Play Protect enabled, and deny permissions that do not match the app's purpose. For legitimate apps, use official links generated with our [URL QR code generator](/url-qr-code-generator). Verify app download codes using our [QR safety checker](/qr-safety-checker) guidelines.
4. For Developers
Publish your app through official stores and link to the store listing in QR campaigns using our [UTM builder](/utm-builder) for tracking—to avoid training users to sideload. Size codes with our [QR size calculator](/qr-size-calculator), follow our [QR placement guide](/qr-placement-guide), and test with our [printed QR tester](/printed-qr-tester).
Putting this into practice
Start with the smallest real test you can run. Generate the code, print it at the exact size you plan to use, and scan it with two different phones in the lighting where it will live. Check that the destination page loads quickly on a mobile connection and that the call to action next to the code tells people what they will get. If anything feels slow or unclear, fix it before you print a full batch, because reprints cost more than a short test. Keep a note of the size, material, and placement that worked so the next batch starts from a proven setup.
Common mistakes to avoid
The most common mistakes are easy to avoid once you know them. Long payloads make modules tiny, low contrast makes edges hard to read, and text placed too close to the border eats the quiet zone the scanner needs. Covering a corner finder pattern with a logo or a sticker breaks detection entirely, and a code placed behind glare or on a curved surface fails even when the print is perfect. Review each of these points on a proof copy, and treat any failure as a reason to adjust the design rather than a reason to blame the scanner.
Quick checklist
- Keep the payload as short as practical so modules stay large.
- Keep dark modules on a light background with strong contrast.
- Leave a clear quiet zone on all four sides of the symbol.
- Test the printed code at the real viewing distance and lighting.
- Confirm the destination page loads fast on a phone.
- Recheck the code after any change to the link, design, or placement.
