Dirty Markup

http://www.dirtymarkup.com/

DirtyMarkup combines the power of HTML Tidy, CSS Tidy, JS Beautify, and the Ace editor to effortlessly clean up your messy code.

Pencil Project

http://pencil.evolus.vn/

Pencil is built for the purpose of providing a free and open-source GUI prototyping tool that people can easily install and use to create mockups in popular desktop platforms.

Platform:

• Mac
• Windows

For wireframe-creation. It can also create prototypes by linking different pages of your project. So you can do something like “activate this and that will happen.”