Sarabun

Sarabun is a sans-serif typeface designed by Suppakit Chalermlarp, added to Google Fonts in 2013. It's available in 8 weights.

This is one of 4 character sets supported (latin, latin-ext, thai, vietnamese). Being free and open source, it's a great choice for web projects, print, and branding — and it's a frequent result in the font finder.

Putting it on a site? See the guide to using custom fonts on the web.