QR Code Generator API

A simple and customizable QR Code Generator API built with FastAPI and Python.

Features

• Generate QR codes from text or URLs
• GET and POST endpoints
• Customizable QR code options (size, color, border, error correction, etc.)
• Support for PNG, SVG, and JPEG formats
• Downloadable filenames
• Return QR code as base64 string in JSON
• Decode QR codes from images
• Batch QR code generation (ZIP)
• QR code with logo/image overlay
• Artistic QR codes with custom colors (using segno)
• User-friendly error messages and validation

Requirements

• Python 3.7+

Installation

1. Clone the repository or download the code.
2. Install dependencies:

   pip install -r requirements.txt

Quickstart

1. Start the API server:

   uvicorn main:app --reload

   The API will be available at http://127.0.0.1:8000.

2. Generate a QR code (GET):

   curl -o qr.png "http://127.0.0.1:8000/generate?data=HelloWorld"

   This saves a PNG QR code for "HelloWorld" as qr.png.

3. Generate a QR code (POST, JSON):

   curl -X POST "http://127.0.0.1:8000/generate" \
        -H "Content-Type: application/json" \
        -d '{"data": "https://example.com", "format": "svg"}' \
        -o qr.svg

   This saves a SVG QR code for "https://example.com" as qr.svg.

4. Decode a QR code image:

   curl -X POST "http://127.0.0.1:8000/decode" \
        -F "file=@qr.png"

   This will return the decoded data from qr.png.

---

Running the API

Start the server with:

uvicorn main:app --reload

The API will be available at http://127.0.0.1:8000.

Usage

1. Generate QR Code (GET)

Generate a QR code with default options by passing data as a query parameter:

GET /generate?data=HelloWorld

Options:

• data (required): Data to encode
• format: png, svg, jpeg (default: png)
• filename: Download filename (optional)
• base64: If true, returns base64 string in JSON (optional)

Example:

GET /generate?data=HelloWorld&format=svg&filename=myqr&base64=true

2. Generate QR Code (POST)

Send a JSON payload to customize the QR code:

POST /generate
Content-Type: application/json

{
  "data": "https://example.com",
  "box_size": 8,
  "border": 2,
  "fill_color": "blue",
  "back_color": "yellow",
  "version": 2,
  "error_correction": "H",
  "format": "jpeg",
  "filename": "site",
  "base64": true
}

Response: PNG, SVG, or JPEG image, or JSON with base64 string.

3. Decode QR Code (POST)

Decode a QR code from an uploaded image (PNG or JPEG):

POST /decode
Content-Type: multipart/form-data
file: <your_qr_code.png>

Response:

{
  "results": [
    { "data": "decoded text or URL", "type": "QRCODE" }
  ]
}

4. Batch QR Code Generation (POST)

Generate multiple QR codes and receive a ZIP file:

POST /batch_generate
Content-Type: application/json

{
  "items": [
    {"data": "https://example.com", "format": "png", "filename": "site"},
    {"data": "Hello World", "format": "svg"},
    {"data": "Another", "format": "jpeg", "filename": "another_qr"}
  ]
}

Response: ZIP file containing all QR codes.

5. Generate QR Code with Logo (POST)

Overlay a logo image in the center of the QR code:

POST /generate_with_logo
Content-Type: multipart/form-data

Fields:
- data: The data to encode (required)
- logo: The logo image file (PNG/JPEG, optional)
- box_size, border, fill_color, back_color, version, format, filename, base64 (optional)

Example using curl:

curl -X POST "http://127.0.0.1:8000/generate_with_logo" \
     -F "data=Hello with logo" \
     -F "logo=@logo.png" \
     -F "format=png" \
     -o qr_with_logo.png

Best Practices for QR Codes with Logos

• Always use error correction level 'H' (the API does this by default for logo QR codes). This allows up to 30% of the QR code to be obscured and still be readable.
• Keep the logo small: The logo should cover no more than 1/6 of the QR code area for best scan reliability.
• Ensure good color contrast: The QR code and logo should have strong contrast with each other and the background for easy scanning.

6. Generate Artistic QR Code (POST)

Create a QR code with custom colors and style using segno:

POST /generate_artistic
Content-Type: multipart/form-data

Fields:
- data: The data to encode (required)
- dark: Foreground color (default: #000)
- light: Background color (default: #fff)
- border: Border size (default: 4)
- scale: Size multiplier (default: 10)
- error_correction: L, M, Q, H (default: L)
- format: png or svg (default: png)

Example using curl:

curl -X POST "http://127.0.0.1:8000/generate_artistic" \
     -F "data=Artistic QR" \
     -F "dark=#1a73e8" \
     -F "light=#fffbe7" \
     -F "format=svg" \
     -o artistic_qr.svg

Customization Options (POST)

Field	Type	Default	Description
data	string	required	The data to encode in the QR code
box_size	int	10	Size of each QR box
border	int	4	Border thickness
fill_color	string	"black"	Color of the QR code
back_color	string	"white"	Background color
version	int	1	QR code version (1-40)
error_correction	string	"L"	Error correction: L, M, Q, or H
format	string	"png"	Output format: png, svg, jpeg
filename	string		Download filename (optional)
base64	bool	false	Return as base64 string in JSON
logo	file		Logo image for overlay (with_logo only)

API Documentation

Interactive docs available at:

• Swagger UI: http://127.0.0.1:8000/docs
• ReDoc: http://127.0.0.1:8000/redoc

License

MIT