Mona & Hubot Sans

Two free fonts from Github suitable for bold design.

Lack font

Lack is a contemporary display typeface with 4 styles (Regular, Italic, Line, Line Italic).

Geist font

A typeface specifically designed for developers and designers.

Fontshare

Fontshare is a free fonts service launched by the Indian Type Foundry. Beautiful, free fonts.

Atipo Foundry

The best free and pay what you want font library.