User interface design or user interface engineering is the design of computers, appliances, machines, mobile communication devices, software applications, and websites with the focus on the user’s experience and interaction. Interface design is involved in a wide range of projects from computer systems, to cars, to commercial planes; all of these projects involve much of the same basic human interactions yet also require some unique skills and knowledge.
In this article I am presenting a collection of user interface design tools for web designer. I hope that you will like this wonderful collection. Feel free to share your comments with me.
1. Flex 3 Stencil
Includes all Flex components from Flex 3 Style Guide: panels, data grid, buttons, fields, links, toggle, menu, scrolls, accordion, tabs, list, data picker, tool tip, errors etc.

2. User Interface Design Framework
A free User Interface Design tool for Web Designers.

3. Mockingbird
Mockingbird is an online tool that makes it easy for you to create, link together, preview, and share mockups of your website or application.

4. Best Practice UX Forms Stencil
This forms contain different button layouts, a progress indicator, captcha code input field, labels and more.

5. Snippet Library
A library of user-submitted and reviewed snippets and code tutorials from a variety of programming languages.

6. HTML Assets
This is a collection of free Javascript code snippets. It has scripts setting the default focus on page elements (useful for HTML forms), scripts to auto-jump to the next form field when the current form field is full, and scripts to display the current date and time, reload the web page, print the web page, view the page source, close the browser window, and go back to the browser’s previous web page.

7. Slidenote
SlideNote is a customizable, flexible jQuery plugin that makes it easy to display sliding notifications on your website or in your web application. It’s also available as a WordPress plugin.

8. Javascript Kit
One of the original javascript snippet libraries on the Internet.

9. Serena Prototype Composer
Serena Prototype Composer makes it possible to simulate how an application will look and function before any code is ever written.

10. Lumzy
Lumzy is a quick mockup and creation and prototyping tool.

11. Gliffy
Gliffy free wireframe software makes it easy to create website wireframes and to share web mockups with anyone.

12. ForeUI
ForeUI is an easy-to-use UI prototyping tool, designed to create mockup / wireframe / prototypes for any application or website you have in mind. With ForeUI, your prototype project will be skinnable.

13. Dhtmlz
DHTMLX is a JavaScript library that provides essential functionality for building cross-browser, Ajax-based user interfaces. Develop impressive web applications faster with a set of ready-to-use UI widgets.

14. Hot Gloo
The Online Wireframe Application.

15. ALL In One Web Elements Kit
Complete set of web elements you may find very useful for your upcoming project. A huge set of various web elements, easy to modify trough layer styles.

16. Mocklinkr
Use mocklinkr to convey your static mockups as a linked-up and clickable website to impress your clients.

17. Android Asset Studio
The launcher icon generator will create icons that you can use in your Android application, from a variety of source images. To begin, simply enter the input details below. Output will be shown below.

18. Patternry
Patternry is a user interface design pattern library aimed to help solve common interface design problems.

19. Wireframe Magnets (DIY Kit)
This DIY magnet template is based on the Konigi wireframe stencils and includes 3 sheets of elements that might be useful in whiteboard prototyping.

20. Eclipse Stencil for OmniGraffle
This stencil enables you to easily prototype Eclipse (wizard) dialogs with OmniGraffle.

21. DesignerVista
Design Professional Quality GUI Mockups using tremendous number of native controls, widgets, clip art, icons, etc. available right in the application.

22. Facebook Applications
A pretty sizable collection of Facebook related elements to use in creating wireframes for Facebook applications.

23. Fivesecondtest
Fivesecondtest helps you fine tune your landing pages and calls to action by analyzing the most prominent elements of your design.

24. The Pencil Project
The Pencil Project’s unique mission is to build a free and opensource tool for making diagrams and GUI prototyping that everyone can use.

25. iPlotz
iPlotz allows you to rapidly create clickable, navigable mockups and wireframes for prototyping websites and software applications.
