Zen Form
Add distraction mode for forms
Parsley.js
Validate your forms, frontend, without writting a single line of javascript!
Alpaca
Easy HTML5 Forms for jQuery
Validate.js
Lightweight JavaScript form validation library inspired by CodeIgniter.
Content Tools
A JS library for building WYSIWYG editors for HTML content.
Garlic.js
Garlic.js allows you to automatically persist your forms' text and select field values locally, until the form is submitted. This way, your users don't lose any precious data if they accidentally close their tab or browser.
Progression.js
A jQuery plugin that gives users real time hints & progress updates as they complete forms
jQuery Super Labels
Give your forms a helping of awesome!
Autosize
jQuery plugin for dynamic textarea sizing
Expanding Textareas
jQuery plugin for elegant expanding textareas
Resumable.js
A JavaScript library for providing multiple simultaneous, stable, fault-tolerant and resumable/restartable uploads via the HTML5 File API.
Formbuilder
[Needs Maintainer] Formbuilder is a small graphical interface for letting users build their own webforms.
Zxcvbn
zxcvbn, named after a crappy password, is a JavaScript password strength estimation library. Use it to implement a custom strength bar on a signup form near you!
jQuery Textcomplete
Introduce autocompleting power to textareas, like GitHub comment forms have.
jQuery Smart Auto Complete
AutoComplete plugin with smart defaults and flexibility to customize
Validatr
Cross Browser HTML5 Form Validation.
Completely
A fresh take on autocompletion for a wonderful user experience