Redux is a simple, truly extensible and fully responsive options framework for WordPress themes and plugins. Ships with an integrated demo.
The ultimate toolkit for theme developers using the WordPress Customizer
For users who have a product with Redux Framework that a developer shipped with developer mode on (IE, annoying update notices and links to GitHub).
Simple yet flexible Theme Options plugin for any damn theme.
Build your customizer without writing codes. With kirki and this plugin you can create customizer with some clicks.