Helvetica Neue

Helvetica Neue is a sans-serif font. It goes well with Proxima Nova, Lucida Grande, Georgia, Helvetica, DIN, Avenir, Open Sans, Adelle, Trade Gothic and Museo Sans. If you're thinking about using Helvetica Neue then try 50px for headers. Give 16px a shot for content.

People commonly tag it as sans serif, modern, app, photo, agency, design, simple, blog, clean and portfolio. You can get it from MyFonts.