Google Fonts is a repository of free, open-source fonts that you can use when designing a website. This article lists 6 of the most interesting fonts available, practical examples of the fonts in use and a few tips to optimize websites using Google Fonts.
This font is great for headlines and menu. Tech site Hongkiat has put Rajdhani in good use in their clean, neat main navigation menu. More info/Download
Probably the most popular and used Google Font, Roboto is a great alternative to web safe fonts like Arial or Helvetica.
Another very clean font which will be the perfect successor to the endless amounts of Arial and Helvetica fonts on websites. Libre Franklin is the font I chose for the 2017 version of CatsWhoCode theme.
Open Sans is optimized for print, web, and mobile interfaces, and has excellent legibility characteristics in its letterforms. No wonder why many designers rely on it when it comes to building beautiful and readable websites.