What font does GitHub use? The closest font you can get for the GitHub logo is Collegiate font.…
What font does Addthis use? The closest font you can get for the Addthis logo is Helvetica Neue LT Std 65 Medium font.
Helvetica grew in popularity throughout the 1960s and 1970s
Free alternative fonts for Addthis logo:
The closest free font you can get is Goulong Bold Font.
About free fonts:
Fonts by Graham Meade