As the mobile web transforms the development process, a few free mini tools have surfaced in our arsenal to aid building advanced web properties in an ever-changing world.
TinyPNG
This web-based PNG compression service really shrinks those bloated PNGs while retaining the alpha layer too.
http://tinypng.org/
Responsivator
This handy service displays a number of configurable screen sizes for responsive testing.
http://dfcb.github.com/Responsivator/
Adobe Edge Inspect
Part of a suite of tools for contemporary web development, Adobe again leads the way in comprehensive toolsets.
http://html.adobe.com/edge/inspect/
Moqups
A very advanced and simple-to-use web tool for creating a wide array of wireframe mockups.
https://moqups.com/
Snipplr
Get your many, many snippets of code for all manner web dev needs, including HTML, CSS, PHP, jQuery, and more.
http://snipplr.com/
fontBomb
For when you’re going insane from all the multi-device madness, plant a few fontBombs to get some much needed relief!
http://fontbomb.ilex.ca