QR Code Generator

What a QR Code Actually Contains

A QR code is not a link to a lookup service. It is the data itself, encoded directly into a grid of black and white modules. When a phone camera reads one, it decodes the pattern into text on the spot. That text might be a web address, a phone number, a Wi-Fi configuration or a plain sentence, and nothing needs to be contacted for the decoding to happen.

This has a practical consequence worth understanding. A QR code generated here is permanent and self-contained. It will still work in five years whether or not this website exists, because the information lives in the pattern rather than on our server. It also means the code cannot be edited after printing; changing the destination requires generating a new code.

Static Versus Dynamic Codes

Commercial QR services often sell "dynamic" codes, which are worth understanding before you pay for one. A dynamic code encodes a short redirect URL owned by the provider. Scanning it hits their server, which then forwards the visitor to your real destination. This allows the destination to be changed later and scans to be counted.

The trade-off is dependency. The code stops working entirely if the provider shuts down, changes their domain, or the subscription lapses, and every scan passes through a third party who sees who scanned, when and from roughly where. For a poster that will be reprinted anyway, or a link you control, a static code avoids all of that. If you need editability, you can get most of the benefit by pointing a static QR code at a short URL on your own domain and changing the redirect yourself.

Error Correction and Why Codes Still Scan When Damaged

QR codes use Reed-Solomon error correction, which stores redundant information so the code survives damage. There are four levels, and the choice is a genuine trade-off: higher correction means more resilience but more modules, so either a denser code at the same size or a larger code for the same density.

This is also why a logo can be placed in the middle of a code at all. The logo is damage, and the error correction absorbs it. Keep any overlay under roughly 20 per cent of the total area and use level Q or H if you are covering the centre, or you will produce a code that scans on your desk and fails on a wall.

Sizing for Print

The single most common QR failure in the physical world is a code printed too small for the distance it will be scanned from. A workable rule of thumb is that the code should be about one tenth of the intended scanning distance. A code read from arm's length, roughly 30 cm, needs to be around 3 cm across. One on a wall poster scanned from three metres needs roughly 30 cm.

Two more print rules matter. Always leave a quiet zone, a margin of clear background at least four modules wide on all sides, because scanners use it to find the code's boundary; a code butted against text or a border often fails. And keep contrast high with a dark code on a light background. Inverted codes, light on dark, are unreliable on many scanners, and low-contrast colour combinations such as mid-grey on beige frequently fail under imperfect lighting.

Keeping the Data Short

More characters mean more modules, which means a denser pattern that requires a better camera and a closer approach. Shortening the encoded text is the cheapest possible improvement to scan reliability. Drop the https:// prefix if your scanner audience is modern, remove tracking parameters where you can, and prefer a short path over a long one. A link with sixty characters of campaign parameters produces a visibly denser code than a clean twenty-character URL.

Common Uses Beyond Links

• Wi-Fi access. Encoding a network name and password lets guests join without typing anything, which is why this appears in cafés and holiday rentals.
• Contact details. A vCard encoded in a code lets someone save your full contact record from a business card in one scan.
• Payments. UPI and similar systems encode a payee identifier and optionally an amount, which is the basis of counter-top payment stickers.
• Asset and inventory tags. Equipment labelled with a code linking to its maintenance record, typically printed at high error correction because the surface takes abuse.
• Event tickets and check-in. A unique reference per attendee that a scanner validates against a list.

A Word on Safety

Because a QR code is unreadable to humans, it is an effective way to disguise a destination, and malicious codes stuck over legitimate ones on parking meters and payment terminals are a real and growing problem. Sensible habits: check the URL your phone previews before opening it, be suspicious of any code that leads to a page asking for payment or login credentials, and look at physical codes for signs that a sticker has been placed over the original. If you are the one publishing codes, printing the destination domain in readable text beside the code helps your audience verify it.

Generated Entirely in Your Browser

The text you encode may be a private Wi-Fi password, a personal phone number, an internal document link or a payment identifier. None of it needs to reach a server to be turned into a grid of squares, and here none of it does. The code is computed in your browser and drawn to a canvas on your own device, then downloaded from that canvas. Nothing you type is transmitted, logged, stored between visits or attached to an analytics event, and no record exists of any code you have made. Because the resulting image is static and self-contained, it will keep working indefinitely regardless of what happens to this site. Load the page, disconnect from the internet, and you can still generate and download a working code.

Frequently Asked Questions