Here’s a humble selection of free sans fonts from Google that I have found to work really well in digital media. Take a look!
Merriweather Sans is a low-contrast semi-condensed sans-serif text typeface family designed to be pleasant to read at very small sizes. It is traditional in feeling despite the modern shapes it has adopted for screens. There are 8 styles: Light, Regular, Bold, and ExtraBold weights in Roman and Italic styles.
Lato is a sans serif typeface family with classical proportions (particularly visible in the uppercase) to give the letterforms familiar harmony and elegance. The semi-rounded details of the letters give Lato a feeling of warmth, while the strong structure provides stability and seriousness. There are 5 different weights with matching Italics.
Source sans pro
Source Sans Pro is Adobe’s first open source typeface family. It is a sans serif typeface intended to work well in user interfaces. Features 6 weights with matching Italics.
The Fira font family comes in a Sans Serif with 4 weights (Light, Regular, Medium and Bold) all accompanied by italic styles.
Ek Mukta is a Unicode compliant, versatile, contemporary, humanist, mono-linear typeface available in seven weights, supporting Devanagari and Latin scripts. Available in 7 weights.
A close relative of Martel Serif, a readable typeface whose glyph proportions are inspired by traditional writing and calligraphic styles.
Khula is a sans typeface in 5 different weights that works beautifully both in small and large sizes or paragraphs and headlines. It is readable with large x-height, large counters and short ascenders and descenders.