How to Generate QR Codes

Problem

You need to encode a URL or text into a QR code for scanning by mobile devices.

Prerequisites

• Understanding of QR code structure
• Knowledge of error correction levels

Steps

1. 1. Prepare the data to encode

   Determine the content: a URL, plain text, contact info (vCard), or WiFi credentials. Keep the data as short as possible, as longer data requires a larger QR code that is harder to scan. For URLs, use short links if possible.

   Input

   https://example.com/page

   Output

   data ready

2. 2. Choose error correction and size

   Select an error correction level: L (7%), M (15%), Q (25%), H (30%). Higher levels allow more damage but increase size. Choose the smallest size that fits your data at the chosen error level. For printed codes, use Q or H.

   Input

   level: M, size: 256px

   Output

   settings configured

3. 3. Generate and test the QR code

   Generate the QR code as an image (PNG, SVG) or data URL. Test it with multiple QR scanner apps on different devices. Ensure it scans reliably at the intended display size. Add a quiet zone (white border) around the code for reliable scanning.

   Input

   generate QR

   Output

   PNG image, tested

Expected result

A scannable QR code image that encodes the specified data.

Common errors

QR code too dense to scan

Reduce the data length, lower the error correction level, or increase the physical size of the printed code.

Missing quiet zone

QR codes require a white border (quiet zone) of at least 4 modules. Without it, scanners may fail to detect the code.

Troubleshooting

• If scanning fails, increase the image resolution and ensure sufficient contrast (black on white).
• Test at the actual display size; a code that works on screen may be too small when printed.

Security limits

• QR codes can encode malicious URLs. Users should see the URL before visiting. Do not auto-open QR-encoded URLs.