Show HN: ShadowCat – file transfer through QR Codes in a Browser

ShadowCat is a browser-based tool that enables offline file transfer between devices using QR codes, designed for older phones with working cameras but broken wireless radios. Users can encode files into sequences of QR codes displayed at a chosen frame rate, which another device scans and decodes to reconstruct the original file with CRC verification. The tool is fully contained in a single HTML file, works entirely offline, and includes configurable compression, error correction, and chunk sizing to optimize transfer speed and reliability.