js canvas captcha
https://thejackalofjavascript.com/building-a-captcha-using-html5-canvas/
https://arvindr21.github.io/captcha/
https://arvindr21.github.io/captcha/catpcha.js
https://github.com/zxdong262/canvas-captcha
https://www.npmjs.com/package/canvas
https://github.com/Automattic/node-canvas
https://www.cairographics.org/