Scanning and device compatibility

What scans what, from iPhone cameras to warehouse imagers.

• Camera permissions and QR scanningWhy web QR scanners need HTTPS, how per-site camera grants work, what blocked looks like, and why every scan page should offer a file-upload fallback.
• How QR scanning works in a browsergetUserMedia plus a decoder: the native BarcodeDetector API or a wasm library. How web QR scanners work, and how to tell if yours uploads your camera.
• How to scan a damaged QR codeRescue a torn, scratched or faded QR code (crop, flatten, boost contrast, cover damage with white), and know when the data is genuinely gone.
• How to scan a QR code from a photoDecode a QR code from your gallery with Live Text, Google Lens or a browser upload, and rescue photos that will not decode with crop, straighten, contrast.
• How to scan a QR code from a screenshotThe camera cannot scan its own screen: decode the screenshot instead. Live Text on iPhone, Google Lens on Android, or upload it to a browser scanner.
• How to scan a QR code on a computerNo desktop OS ships a real QR scanner. Decode codes on Windows, macOS or Linux with a browser-based scanner: upload a screenshot or use the webcam.
• How to scan a QR code on AndroidPoint the camera, or use Google Lens if nothing happens. Android 13 adds a quick settings scanner tile. Every reliable route, whatever the manufacturer.
• How to scan a QR code on any deviceOn iPhone and Android, open the camera app and point it at the code: a banner appears with the destination. No separate app is needed on any current…
• How to scan a QR code on iPhoneiPhones scan QR codes from the Camera app: nothing to install since iOS 11. Every route covered, including Photos, Live Text and the Control Centre scanner.
• How to scan a QR code on the same phoneThe camera cannot see its own screen. The full same-phone playbook: screenshot routes, long-press shortcuts, and why on-screen codes need a link fallback.
• How to scan a QR code without an appYou have not needed a QR scanner app since 2017. Native camera scanning on iPhone and Android, browser scanning on desktop, and the few real exceptions.
• QR scanning on a MacmacOS has no built-in QR scanner: Preview cannot decode codes. The working options (browser scanner, webcam, Continuity Camera) ranked honestly.
• QR scanning on iPadiPads scan QR codes exactly like iPhones: Camera app since iOS 11. The real differences are ergonomic, plus how to use an iPad as a kiosk scanner.
• QR scanning on Linuxzbarimg one-liners, zxing-cpp for stubborn codes, and the browser fallback: the reliable ways to decode QR codes on any Linux desktop or server.
• QR scanning on WindowsThe Windows Camera app has a barcode mode, but the screenshot-to-browser flow covers more cases. Every way to decode a QR code on a Windows PC.
• Which phones can scan QR codes nativelyThe compatibility table: iPhones since iOS 11 (2017), Android via camera or Lens since roughly 2018, and the honest long tail of feature phones.
• 2D imager vs laser scannerWhy a laser scanner physically cannot read a QR code, what a 2D imager does differently, and what warehouses migrating from 1D barcodes need to check.
• Batch scanning many QR codesThree workflows that scale (a keyboard-wedge imager into a spreadsheet, a phone app with batch mode, or a decode API in a loop), plus dedup and timestamps.
• Do you need a QR scanner app?Not since 2017: every current phone scans from the camera. What standalone apps genuinely add, how free ones pay for themselves, and the no-install option.
• Google Lens and QR scanningHow to scan QR codes with Google Lens from the camera, screenshots and images in other apps, and where your image goes, compared with a local decoder.
• Hardware barcode scanners and QR codesWhen a dedicated 2D imager beats a phone (decode latency, motion tolerance, keyboard-wedge output), and the scans-per-day threshold where buying one pays.
• Motion blur and QR scanningThe arithmetic of movement: why drive-by scanning fails, how much handheld shake a scan tolerates, and how industrial imagers freeze motion entirely.
• Offline QR scanningDecoding a QR code never needs the internet: the camera does it locally. Which payloads work fully offline, and the airplane-mode test that proves it.
• QR scanning at an angleHow far off-axis a QR code still scans (about 30–45°) why steeper angles fail, and where to mount codes so nobody has to scan at an angle at all.
• QR scanning in low lightWhy QR codes fail in dim rooms (longer exposures turn shake into blur), and what helps: light, bracing, torch technique on gloss, and bigger modules.
• QR scanning on feature phonesWhich feature phones can scan QR codes, what KaiOS actually supports, and the fallbacks (short URLs, SMS, USSD) that keep campaigns working without one.
• QR scanning on smart TVsSmart TVs display QR codes rather than scan them. How the TV sign-in pattern works, how big a code must be across a living room, and why remotes lack cameras.
• QR scanning through glass and screensWhy glass between camera and code causes failed scans (reflections, moiré, double glazing), and the tilt-and-shade technique that fixes most of them.
• Scan latency: why some codes scan instantlyThe decode pipeline runs in tens of milliseconds, so slow scans lose time upstream. The five causes of sluggish codes, ranked, each with its fix.
• Scanning a QR code off a monitorWhy photographing a screen produces moiré that breaks QR scans, the fixes in order (enlarge, back off, tilt), and the dark-mode inversion trap.
• Scanning distance limits for QR codesThe full distance model (a near focus floor around 5–10 cm, a far ceiling from the 10:1 rule), with a size table and how optical zoom changes the limits.
• Scanning multiple QR codes in one framePhone cameras decode one code per frame and pick unpredictably between neighbours. How to lay out adjacent codes, and the APIs that return all of them.
• Scanning QR codes on e-ink displaysE-ink scans like paper (reflective, glare-free, sun-readable), with a 15:1 contrast ratio that clears the bar. The catches: light needed, refresh ghosting.
• Scanning QR codes with a webcamHow to scan a QR code with a webcam in the browser, where to hold the code, why fixed-focus webcams blur close-ups, and what 720p can actually resolve.
• Screen brightness and QR scanningDisplayed QR codes live and die by brightness: why paper beats screens outdoors, why auto-brightness sabotages scans, and the wallet-pass pattern to copy.