Prototyping

To sort: http://www.cooper.com/prototyping-tools

Articles

Responsive Comping: Obtaining Signoff without Mockups, Matt Griffin (alistapart.com)
Rapid Prototyping Tools & Best Practices (hackdesign.org)
Design Better And Faster With Rapid Prototyping (smashingmagazine.com)
Prototyping (usability.gov)
Building Clickthrough Prototypes To Support Participatory Design (smashingmagazine.com)
Start Coding with Wireframes, Matt Griffin (alistapart.com)
Why wireframes should be left to die (creativebloq.com)
HTML Wireframes, Brad Frost
Designing in the Browser: An Efficient Route to Responsive Design (usabilityprofessionals.org)
Introduction to Prototyping (hugeinc.com)
Prototyping Tools and Process Survey results from design teams at Medium, Airbnb, Uber, Apple, Eventbrite, and Pinterest
The Skeptic’s Guide To Low-Fidelity Prototyping
Creating Content Wireframes For Responsive Design By Tom Green

Discussions

What do you use for prototyping? (Designer News)

Wireframing

Interactive prototypes / Click-through wireframes

These tools allow you create wireframes/prototypes in the app itself, as well as making them interactive/clickable.

BYOS (Bring Your Own Screens)

You cannot create mock ups within the app, but using the tools above, you can make your screens clickable.

Invision
Marvel
Solidify, part of the Zurb suite

Mobile app prototypes

Tool reviews

Page-based tools (UXMag.com)
Layer-based and code-based tools (UXMag.com)

Responsive prototypes

Frontend frameworks

Sass: https://github.com/twbs/bootstrap-sass
Themes: http://bootswatch.com
Templates: http://startbootstrap.com/all-templates
Bootstrap without all the debt

http://usablica.github.io/front-end-frameworks/compare.html

Grid: [neat.bourbon.io]((http://neat.bourbon.io/)
UI kit: [bitters.bourbon.io]((http://bitters.bourbon.io/)

Static site generators

staticgen.com is a list for more open-source static site generators

Static site generator written in PHP

HTML prototyping tools

Frontend starter kits

Paper