How decoding works
All decoding happens locally in the browser. The reader locates the three corner finder squares every QR code carries, maps the module grid onto it, then applies the format's Reed-Solomon error correction, which can repair damaged modules depending on the code's correction level (7% to 30% of data). Finally it extracts the payload and renders it as text using the mode the code was encoded in: numeric, alphanumeric, or byte.