QR Code Generation: Complete Guide 2026

A QR code is one of the simplest ways to connect the physical and digital worlds. That's why brochures, business cards, packaging, posters, and even restaurant menus use them. Moreover, once created, a QR code lasts forever — as long as the domain inside it works. Consequently, one correctly made QR code is enough for decades.

What is a QR code and what does it contain?

QR (Quick Response) code is an evolution of the traditional barcode. In particular, unlike a barcode's single dimension, a QR code encodes data both horizontally and vertically. Therefore, it can store significantly more information.

What can you put inside a QR code?

• URL — a web address, e.g. https://siadesign.ee. The most common use case.
• vCard — contact details (name, phone, email, address) saved to a phone with one scan.
• Wi-Fi — network name and password. Consequently, guests can connect without typing.
• Email — opens an email draft with a pre-set address.
• SMS — opens the messaging screen with a number and text.
• Text — any text, up to ~4,296 characters.
• Geolocation — GPS coordinates that open a map.

QR code anatomy: how does a scanner read it?

Before generating codes, it's helpful to understand how a QR code is structured. Specifically, every QR code consists of defined structural elements that the camera detects and decodes.

Core components

• Position markers (finder patterns) — three large squares in the corners. They help the camera quickly identify a QR code and determine its orientation. Therefore, the code reads correctly even when rotated.
• Timing patterns — alternating black and white squares between position markers. They help the scanner determine the exact size of each data module.
• Data modules — the encoded content itself. Each black or white square is one bit. Consequently, the more data, the more squares and denser the code.
• Quiet zone — empty area around the code (min 4 modules). This is essential! Without it, the scanner may not recognize the code.
• Alignment patterns — in larger QR codes (version 2+), smaller squares appear to help correct curvature.
• Format info — error correction level and mask pattern are encoded directly into the code.

Error correction levels

One of the QR code's most ingenious features is built-in error correction. This means that even if part of the code is damaged, dirty, or covered by a logo, the scanner can still recover the data. Therefore, choosing the right error correction level is critically important.

Four levels

Free QR code generation: 4 best methods

Now let's get practical. Below are 4 free methods for creating QR codes — from web tools to the terminal.

1. Online generators

• QRCode Monkey — free, ad-free, allows color customization, shapes, and logo embedding. Exports PNG, SVG, PDF, and EPS. Therefore, the best choice for visually customized codes.
• goQR.me — simple and fast. Works for URL, vCard, SMS, and Wi-Fi codes. Exports PNG and SVG.
• Nayuki QR Generator — open-source, technical. Shows code size and version details. Suitable for developers.

2. Terminal (macOS / Linux)

If you have qrencode installed, you can create a QR code with a single command:

# Install (macOS)
brew install qrencode

# Generate PNG file
qrencode -o qr-code.png -s 10 -m 2 -l M "https://siadesign.ee"

# Explanation:
# -o = output file
# -s = module size in pixels (10 = large and clear)
# -m = quiet zone (margin), min 2
# -l = error correction level: L, M, Q, H
      

The result is a clean qr-code.png file ready for printing. Additionally, you can export as SVG:

# SVG format (vector, scalable, ideal for print)
qrencode -o qr-code.svg -t SVG -l M "https://siadesign.ee"
      

3. With Python

The Python qrcode library lets you generate and customize:

# Install the library
pip install qrcode[pil]
      

import qrcode

# Simple QR code
qr = qrcode.QRCode(
    version=None,  # auto-size
    error_correction=qrcode.constants.ERROR_CORRECT_M,
    box_size=10,
    border=4,
)
qr.add_data("https://siadesign.ee")
qr.make(fit=True)

img = qr.make_image(fill_color="black", back_color="white")
img.save("qr-code.png")
print("✅ QR code generated!")
      

4. QR Server API (in browser)

QR Server offers a free API you can use directly in the browser. Simply open this link:
https://api.qrserver.com/v1/create-qr-code/?size=300x300&data=https://siadesign.ee
Replace the data= parameter with your link. You can save and use the image. However, this method doesn't support logo embedding or visual customization.

QR code customization: colors, logo, shape

Now customization. Many assume QR codes must be black and white. In reality, you can personalize them, but you must follow specific rules to keep the code scannable.

Color rules

• Dark code, light background — always safe. Black on white = best contrast and readability.
• Dark color (e.g. deep purple, dark green, dark blue) on white — works with most scanners. However, always test before printing.
• Light code on dark background — risky! Many scanners only read dark on light. Therefore, avoid light codes on dark backgrounds.
• Gradients and soft transitions — not recommended. Contrast must be sharp and clear.

Adding a logo to the center

• Placing a logo in the center is possible thanks to error correction. Specifically, the logo covers some data modules and error correction compensates for the lost bits.
• Always use Level H (30%) when adding a logo.
• The logo must not cover more than ~25–30% of the code's surface.
• Leave a small white buffer around the logo (2–3 px).
• Test! Scan with at least 3 different devices. Moreover, test from both close (10 cm) and far (30+ cm).

QR codes never expire — ever

This is one of the most common misconceptions. Many believe QR codes "expire" or "stop working." In reality, it's very simple:

• A QR code is simply encoded text. Therefore, there's no server, platform, or service that needs to be "running."
• If the code contains the URL https://yourdomain.com/page, the code works as long as that webpage exists.
• Domain changes or page deleted? The code leads to a 404. But the code itself isn't broken — it still transmits the same text.
• In other words: a correctly made QR code lasts forever.

Print specifications

When a QR code goes to print, certain rules must be followed. Otherwise, the code may not be scannable.

• Minimum size: 2×2 cm (20×20 mm). Smaller codes may be unscannable, especially with higher error correction.
• Recommended size: 3×3 cm for business cards, 5×5 cm for brochures, 10×10+ cm for posters.
• Resolution: at least 300 DPI. Therefore, use vector format (SVG) when possible.
• Quiet zone: minimum 4 modules of empty space around the code. Don't place text or graphics against the code edge.
• Surface: matte surface is better than glossy. Glossy surfaces reflect light and make scanning harder.
• Contrast: black code on white background. Don't print light codes on dark surfaces.

Best practices: QR codes in marketing

• Always add context — "Scan to view portfolio" is much better than a bare code.
• Link to a specific page — not the homepage! If your brochure discusses service X, point the QR code directly to service X page.
• Use UTM parameters — ?utm_source=brochure&utm_medium=qr helps track with Google Analytics how many people came from the code.
• Test before printing — print a proof and scan with at least 3 different phones.
• Mobile-friendly landing page — 99% of scanners are phones. Therefore, the landing page must be mobile-optimized.
• Don't print QR codes just for decoration — every code must have a clear purpose and a clear CTA.

Common QR code mistakes

• Code too small. Printing under 2 cm is risky. Therefore, always check the size.
• QR code on an image. Busy backgrounds interfere with scanning. Always place the code on a clean surface.
• Missing quiet zone. Text or graphics at the code edge make it unreadable.
• Wrong URL. One missing character and the code leads to a 404. Consequently, always test the final result.
• Wrong error correction. Level L with a logo = code won't work.
• Light code on dark background. Many scanners can't read it. Therefore, stick with dark code / light background.

Scanning checklist

• ☐ URL is correct and working
• ☐ Landing page is mobile-friendly
• ☐ Code size ≥ 2×2 cm in print
• ☐ Quiet zone is present (min 4 modules)
• ☐ Error correction matches use case (M for print, H for logo)
• ☐ Tested with 3+ different devices
• ☐ Tested from both close (10 cm) and far (30+ cm)
• ☐ Explanatory text beside the code ("Scan for portfolio")
• ☐ UTM parameters for tracking results
• ☐ Contrast is sufficient (dark code, light background)

FAQ: QR Codes