If you are working on a web project and want to use a Font free and free, then you should take a look at Fira Sans.
Fira is the font used in Firefox OS, the operating system for smart phones de Mozilla. Erik Spiekermann and Ralph du Carois designed Fira with the mobile devices in mind, so you don't have to worry if your project will be displayed on a wide variety of different terminals, the readability it will always be good.
Fira is distributed in four styles (light, regular, medium and bold) and includes their respective variants in italics. The package —which you can download below— also includes the monospaced font.
You can download Fira Sans from the following links:
Fira is distributed under the license SIL Open Font License.
More information - Download Corrupt Script, the typeface based on Luis Bárcenas, Unveiled the new Firefox logo, Create HTML5 applications for Firefox OS with the Firefox OS Simulator plug-in
Source – Ubunlog, Firefox OS Type face