Web · Beginner
Build a QR Code Generator
Build a generator that encodes text into a scannable QR code image by implementing the data encoding and error-correction steps yourself.
This project turns a string of text into a real, scannable QR code by walking through the actual QR specification rather than calling a library. You implement the data encoding modes, add Reed-Solomon error correction, lay out the modules with the required finder and alignment patterns, and apply a masking pattern before rendering the result as an image. It is worth building because it forces you to read and implement a real-world binary specification, work with bit-level data, and understand the error-correction math that lets QR codes survive smudges and damage. A QR code that scans on a real phone is an impressive, visual proof that you can take a dense spec and turn it into correct working code.
What you build
- Encodes input text into the QR byte (or numeric/alphanumeric) data mode
- Generates Reed-Solomon error-correction codewords for the data
- Places finder patterns, timing patterns, and alignment patterns in the grid
- Arranges data and error-correction bits in the correct zigzag module order
- Applies a mask pattern to balance dark and light modules
- Renders the final matrix to a PNG or SVG image
- Produces a code that scans successfully with a standard phone camera
What it teaches
- Implementing a real binary specification from documentation
- Bit-level data manipulation and packing
- Reed-Solomon error correction and Galois field arithmetic
- Two-dimensional grid layout and module placement rules
- Rendering computed data to an image format
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Take it further
- Support multiple QR versions and automatically pick the smallest that fits the input.
- Implement all eight mask patterns and select the one with the best penalty score, as the spec requires.
- Add numeric and alphanumeric encoding modes for more compact codes.
