What is a QR code used for? 8 practical uses and safety tips
What is a QR code used for? To pass along a web address, Wi-Fi password, payment details, or contact card by scanning an image instead of typing everything out by hand. Most adults do this regularly now. According to an HX Study cited by ITwiz in March 2024, as many as 70 percent of people scan QR codes, and 64 percent of them do it on a regular basis.
This article is for anyone who scans codes in a store, at a parking meter, or on an invoice and wants to know what is actually hiding behind them. I explain how a QR code works, where it comes in handy, how to make one correctly, and how to spot a fake.
Short answer
A QR code is a two-dimensional code that stores text, links, or data like Wi-Fi networks, bank transfers, contacts, or calendar events inside a square made of black and white modules. The code itself is just a carrier, so safety depends entirely on what is stored inside it rather than what it looks like.
How a QR code works
The QR code was invented in 1994 by Denso Wave, a subsidiary of the Toyota group. A team led by engineer Masahiro Hara was looking for a way to track car parts on production lines because standard barcodes held too little data, and workers sometimes had to put up to ten such codes on a single product. Hara came up with the grid idea while playing the game of Go. Denso kept the patent rights but stated they would not enforce them, which is why anyone can create QR codes for free today.
The code is a grid of modules. Three large squares in the corners let a scanner recognize position and rotation, so reading works from any angle. Codes come in 40 versions, starting from the smallest at 21 by 21 modules, and larger versions hold more data.
The code also features built-in redundancy using Reed-Solomon error correction, which means you can still read it even if it gets dirty or partially damaged. When you create a code, you choose one of four levels shown in the table below.
| Level | Data recovery capability | When to use |
|---|---|---|
| L | about 7% | clean screens, short text |
| M | about 15% | standard applications |
| Q | about 25% | prints exposed to dirt |
| H | about 30% | heavy wear, outdoor stickers, centered logos |
A higher error correction level leaves less room for data within a code of the same size. Denso Wave also warns against putting images over the code because any extra smudge on top of that modification can make the code unreadable (manufacturer data, as of 2026).
Step-by-step example: Wi-Fi password in a QR code
You can see this best with a Wi-Fi code because its payload is plain text. Let's say your network is named Home, uses WPA encryption, and has the password coffee;2026.
- You format the text so Android and iOS recognize it:
WIFI:T:WPA;S:Home;P:coffee\;2026;; - You put a backslash before the semicolon in the password because the format uses semicolons to separate fields. The same rule applies to
\,,,:, and"characters. - You turn this text into an image using a QR code generator.
- Your guest opens their camera app (Android 10, iOS 11, and newer), and the phone offers to join the network.
The result: your guest joins the network without you reading out the password. An iPhone will scan a code made on Android, and the other way around. On Android, you can find your own network's code in the Wi-Fi settings after confirming your identity, and iPhones running iOS 16 and up display the password after a verification check.
Trouble starts when you only have the image itself, like a printout from the router, a screenshot, or a file from a friend, and you want to know what is hidden inside.
What QR codes are used for: 8 practical applications
QR codes work best when a person would otherwise have to type something out manually, such as a long URL, password, or account number. People scan them most often in stores and drugstores (38%), on websites (37%), and on public transit (26%), and the main reason is how quickly they provide access to information (51%, HX Study, 2024).
Wi-Fi without spelling out passwords
The code mentioned above lets guests connect to your network with a single scan. It works well at home, in the office, and in public venues because you can change the password and print a new code in a minute.
Transfers and payments
Banking apps often include scan-and-pay features that fill in transfer details automatically once you scan a code (including PKO BP, mBank, Santander, and Credit Agricole, according to data from Fakturowo.pl). Code formats vary, so test it in your specific app first. EPC codes for SEPA transfers are in euros and also depend on whether your bank supports them.
Invoices in KSeF
The National e-Invoice System introduces a QR code on invoice printouts and visualizations. According to the Ministry of Finance, an invoice with a KSeF number gets a code containing that number. An invoice issued offline and not yet sent to the system features two codes: OFFLINE and CERTIFICATE, which lets you verify the issuer. The requirement rolls out in phases (February 1, 2026, April 1, 2026, and January 1, 2027, depending on the taxpayer group), so check your specific date on ksef.podatki.gov.pl.
Public transit tickets
In many cities, buses and subways offer QR codes for validating tickets. Instead of a paper ticket, you show your phone screen or scan a code inside the vehicle.
Menus, stores, and product info
A code on a table or product packaging leads straight to a menu, ingredient list, allergens, or user manual. Manufacturers do not need to print long leaflets, and you do not need to install any app.
Business cards and contacts
A code in vCard format saves a name, phone number, and email address. A single scan creates a contact on your phone without making you type anything from a piece of cardboard.
Events and locations
A code can hold an event date to add to your calendar or map coordinates to open in your navigation app. This comes in handy for invitations and directions.
Lists and files
A code leading to a shared shopping list or a downloadable file acts like a quick way to send something to your phone. The other person just needs a camera.
Common mistakes when making and scanning QR codes
The first mistake is a code that is too small or lacks contrast. Scanning works best in good light with a sharp contrast, and not every scanner can read a light code on a dark background.
The second is a logo larger than the error correction margin. Even level H only recovers about thirty percent of the data, so a massive logo in the middle can break a code that looked fine on screen. Always test on multiple phones.
The third is a dynamic code without a plan. These codes route through a third-party service, so they stop working if your subscription expires, and you cannot fix them once printed. Static codes never expire, but if the destination page vanishes, users see a dead link.
Quishing: how to spot a fake QR code
Quishing is phishing using QR codes. It works because a code does not show a plain text URL, and email filters often treat them as ordinary images.
In Poland, ITwiz covered two major cases from 2023: fake parking meter codes in Krakow that led to a clone of the city road authority website, and fake parking fines with QR codes tucked under wiper blades in Warsaw. Police don't track these crimes separately, but the Ministry of Digital Affairs, CSIRT KNF, and CERT all issue warnings about them.
You can cut down your risk with a few basic habits:
- Check if a public code on a parking meter or bus stop is just a sticker slapped over the original.
- Look at the URL after you scan it, before you tap open, and watch out for lookalike letters.
- Never download files or apps from a scanned code you found in an unknown spot.
- Don't type in your card info or bank login on a site you landed on from a random code.
Scan and Make QR Codes with AQR by AnyServ
AQR (Advanced QR) is a free browser extension by AnyServ for scanning and making QR codes, available in the Chrome Web Store and on the tool's website. Version 2.0.0 is out now, bringing the biggest update since the launch.
You can scan a code by uploading an image, pasting from the clipboard with Ctrl+V, right-clicking an image, or hitting the scan this tab button when a code is on the page. AQR reads up to six codes at once and breaks down the data into fields for Wi-Fi networks with hidden passwords and previews, vCards, calendar events, SEPA transfers, and geolocations. For links, it warns you about URL shorteners, raw IP addresses instead of domain names, or missing encryption, and it always shows the destination domain. Scanning happens entirely inside your browser, so a Wi-Fi password from an image never leaves your computer.
The generator lets you pick the code type, colors, frame, and logo. Once it's built, AQR scans its own code and warns you if the contrast is too low or the logo is too big. That warning is just a guide and not a guarantee because the check uses AQR's own decoder rather than every phone app out there. You can export to PNG, SVG, and A4 PDF, and the batch generator handles up to 300 codes in a single ZIP file. In version 1.1.1, passwords with semicolons generated codes that phones read incorrectly, but version 2.0 handles special characters safely.
AQR only reads QR codes, not barcodes, and it doesn't use your camera to scan. After an update, your browser might ask you to reapprove permissions because of the scripting permission, which is only used by the optional floating button.
AQR is a free extension that reads QR codes from images and web pages, shows you what they contain before you open them, and creates scannable codes.
Frequently Asked Questions
1. What does the QR stand for in QR code?
QR stands for Quick Response. The name points to the original goal of the code: letting a scanner read information instantly.
2. Who invented the QR code and when?
A team led by Masahiro Hara at Denso Wave created the QR code in 1994 to track car parts. Denso kept the patent but decided not to enforce it.
3. How does a QR code differ from a barcode?
A QR code is two-dimensional, meaning it stores data both horizontally and vertically, so it holds much more information than a traditional barcode. AQR only reads QR codes, not barcodes.
4. Can a QR code expire?
A static code stores data right inside the image and never expires on its own, though the website it points to might eventually disappear. A dynamic code routes through a redirect service and can stop working if a paid subscription ends.
5. How can I check where a QR code leads before I open it?
Use a scanner that displays the code contents before opening them and check the target domain. AQR does this for any code loaded from an image or found on a web page.
6. How do I scan a QR code on a computer?
Take a screenshot or copy the code image and load it into a tool that reads codes from pictures. With AQR, you just paste an image from your clipboard, select a file, or click Scan this tab.
These details are for general reference and educational purposes as of October 2026. When dealing with payments, KSeF invoices, or security decisions, double-check current requirements with your bank, the Ministry of Finance, or an appropriate specialist.