jquery.qrcode.js
qrcode generation standalone (doesn't depend on external services)
...It lets developers add QR code output to a webpage without calling an external service or downloading a remote image. The plugin is designed to be lightweight, with a minified and compressed footprint of less than 4 KB. Its basic usage is simple: include the script, create a container element, and call the QR code method with text or options. Developers can configure dimensions such as width and height when generating a code. It is best suited for older jQuery-based sites, simple web utilities, landing pages, and legacy projects that need fast client-side QR generation.