JSON Web Tokens are an open, industry standard RFC 7519 method for representing claims securely between two parties.
JWT.IO allows you to decode, verify and generate JWT.
"Can I use" provides up-to-date browser support tables for support of front-end web technologies on desktop and mobile web browsers.
Remembering what CSS to prefix is hard. Today browsers develop quickly (yay) and things often change (boo). Preprocessors and mixin libraries are not always up to date.
This page has one purpose: simply show what prefixes are needed for a newer CSS property. Need more information? Check the awesome Can I Use or Autoprefixer!
The Nu Html Checker (v.Nu) is a name for the backend of html5.validator.nu, validator.w3.org/nu, and the HTML5 facet of the legacy W3C Validator.