QR Code Generator
Generate QR codes from text or URLs
Introduce contenido para generar el QR
Generador de códigos QR
Crea códigos QR personalizados para compartir URLs, información de contacto, credenciales WiFi y más. El código se genera localmente en tu navegador.
Online QR Code Generator - Create Free Custom QR Codes
What are QR codes and how do they work?
QR (Quick Response) is a two-dimensional barcode invented in Japan in 1994. Unlike linear barcodes that hold around 20 characters, a QR code can carry up to 4,296 alphanumeric characters. It works as a matrix of black and white squares encoding binary data. The three large squares in the corners are position patterns that let a reader decode the code from any angle. Reed-Solomon error correction means the code still reads when part of it is damaged or covered, up to 30% at level H. Modern smartphones scan QR codes natively with the camera, no extra app required.
QR content types: URL, WiFi, vCard and more
QR codes can encode different data types using specific formats. A URL is the most common and opens directly in the browser. WiFi uses the format WIFI:T:WPA;S:name;P:password;; which lets Android and iOS join a network automatically. Email uses mailto:[email protected]?subject=Subject to prefill a message. Phone uses tel:+34600000000 to start a call, and SMS uses sms:+34600000000?body=Message. Geolocation uses geo:latitude,longitude to open a map. A vCard carries full contact details such as name, phone, email and address to add straight to the address book. Each type triggers a specific behaviour on the scanning device.
Best practices for effective QR codes
For QR codes that actually work: use short URLs or a shortener so the code stays simple and easy to scan; keep contrast high, since dark on light scans better than light on dark; print at a minimum of about 2 cm for reliable close scanning and scale up proportionally for posters read from a distance; leave a white margin, the quiet zone, around the code; and test with several devices before printing. For marketing, pair the code with a call to action such as "Scan for a discount". Use the high error correction level (H) when a logo will overlap the code, and make sure the destination URL is mobile friendly.
If you work with this tool, you will probably also find these useful URL Encoder, Image to Base64, UUID Generator, Password Generator.
Frequently asked questions
Can I put a logo in the middle of a QR code?
This tool generates clean QR codes. For a logo, the error correction built into the format lets you cover up to 30% of the code at level H, so you can edit the resulting PNG and place your logo in the centre. Dedicated QR design tools automate that, but any image editor works. Always test the finished code with a logo before you use it in production.
Do QR codes expire or stop working?
The code itself never expires, since it is just encoded data. What can expire is the destination: if the URL no longer exists the code still scans but lands on a 404. QR codes for WiFi, phone numbers or plain text work indefinitely because they depend on no server at all. For URLs, prefer a domain you control long term.
What is the optimal print size for a QR code?
A minimum of 2 by 2 cm for close scanning from a table or a card. For a poster read from a metre away, at least 5 by 5 cm. For signage read from several metres, plan roughly 1 cm of code for every 10 cm of scanning distance. The general rule is that the more data the code carries, the larger it must be printed to keep the modules scannable.
Why does my QR code fail to scan?
The usual causes are low color contrast (try black on white), a code too small for the scanning distance, a missing white margin around it, a curved or glossy surface producing reflections, or damage covering more of the code than the error correction level can absorb. Test with different scanning apps and devices to narrow it down.