The Dead Link Disaster: When Two Hundred Campus Posters Stopped Working in a Fortnight
What happens when a free QR service expires the link on a printed poster, and how a static QR code maker keeps every code permanent, offline and untracked.
QR Code Generator: Links, Text and WiFi, PNG or SVG
Generate a QR code for a link, text, phone number, email, SMS or WiFi. Download a crisp PNG or a scalable SVG. No signup, no watermark, no expiry.
What a QR code generator does
A QR code is a square barcode that holds text: a web address, a phone number, a WiFi password, a message. The generator encodes whatever you type into that pattern and writes it as an image you can print, paste into a slide or put on a poster. Nothing about the code is registered anywhere, so it does not expire and it does not stop working if this site goes away.
The output is either PNG for screens and documents, or SVG for print, where the code has to stay sharp at any size.
How to make one that scans
- Pick the payload: link, plain text, WiFi network, email, SMS or phone number.
- Enter the content. For WiFi, the network name and password; for email, the address, subject and body you want pre-filled.
- Keep the default contrast: dark modules on a light background. An inverted code fails on many scanners.
- Set the size, then download PNG for a screen or SVG for print.
- Scan it with two phones before you print a thousand of them. The failure mode of a QR code is silent.
A worked example
A guest WiFi code for a cafe holds the network name and password, which is about 50 characters. That stays a dense but simple code, readable on a card at 20 mm wide. A link to a menu with campaign parameters can run past 150 characters, and the same 20 mm card then becomes unscannable because each of the modules is under 0.3 mm and a phone camera cannot resolve it.
The fix is either a larger print or a shorter link. On paper, keep modules at 0.5 mm or more, which for a 25x25 module grid means about 13 mm, plus a quiet margin around the code. On a phone screen, 300 px wide is a comfortable minimum.
Mistakes worth avoiding
A logo in the middle without error correction. Covering more than a small part of the code stops it decoding; the safer choice is no overlay at all.
Placing a code on a dark background. Scanners expect light background, dark modules; inverted codes work on some phones and fail on most.
Cropping the white margin. The quiet zone is part of the code as far as a scanner is concerned.
Encoding a URL that you might change. The code contains the text, so a new destination means a new code. If the address has to change later, point the code at a short link you control instead.
Where your data goes
Nowhere. The code is generated in this tab, which is why a WiFi password or an internal link never leaves the device it was typed on.
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Frequently asked questions
Do the QR codes expire or carry a watermark?
No. Every code is generated locally in your browser from the text you type, so there is no redirect service in the middle, no expiry date, and no branding added. A static QR code you download today keeps working forever.
Should I download PNG or SVG?
Use PNG for chat, presentations, and social posts at a fixed size. Use SVG when the code will be printed on packaging, posters, or shop signage, because vector output stays razor sharp at any size and can be recoloured in design software.
Which error correction level should I pick?
Medium (M) is right for most screens. Choose Quartile or High when the code will be printed on a curved, shiny, or dirty surface, or when a small logo sits on top; higher levels survive more damage but make the pattern denser.
Can I build a WiFi QR code without exposing the password?
The WiFi mode encodes the network name, password, and encryption type into the code. Anyone who scans it joins the network, so share it only with people you would give the password to. Nothing is sent to a server; the code is rendered on your device.
Do these QR codes expire?
No. The code is the data, encoded directly. There is no redirect, no account and no tracking, so it works forever, including offline.
How much text can a QR code hold?
A few thousand characters at the densest setting, but practical limits are much lower: dense codes need to be printed larger to stay scannable. For a poster, keep the payload under about 150 characters.
PNG or SVG?
SVG for anything printed, because it scales without blurring. PNG for screens, documents and anywhere that does not accept vector files. Print PNGs at 1000 px wide or more.
Can I put my logo in the middle?
Only with error correction and a small overlay. The generator does not add one for you, and a code with a large logo is the single most common reason a printed code stops scanning.
Why does my WiFi code not connect?
Usually a wrong security type or a hidden network. The code carries the exact strings typed, so the network name has to match precisely, including capitals.