Quill
A cross browser rich text editor with an API
Selectize.js
Selectize is the hybrid of a textbox and <select> box. It's jQuery based and it has autocomplete and native-feeling keyboard navigation; useful for tagging, contact lists, etc.
Filepond
🌊 A flexible and fun JavaScript file upload library
Alpine
A rugged, minimal framework for composing JavaScript behavior in your markup.
Switchery
iOS 7 style switches for your checkboxes
Angular Validation
Customizing Form Valid Message in AngularJS
Angular Formly
JavaScript powered forms for AngularJS
React Editext
Editable Text Component for React Apps
Form2js
Javascript library for collecting form data
Sisyphus
Gmail-like client-side drafts and bit more. Plugin developed to save html forms data to LocalStorage to restore them after browser crashes, tabs closings and other disasters.
Forms Angular
Probably the most opinionated framework in the world
Fancy Input
Makes typing in input fields fun with CSS3 effects
Magicsuggest
Multiple Selection Combo Box using Bootstrap 3
Unform
Performance-focused API for React forms 🚀
jQuery Autotab
A jQuery plugin that provides auto tabbing and filtering on text fields in a form
Formbuilder
[Needs Maintainer] Formbuilder is a small graphical interface for letting users build their own webforms.
Taggle.js
Form-ready dependency-less tagging.