No — Proto Mono isn’t listed as a free font. ATK Studio releases it, so licence options and pricing sit on their site.
Proto Mono is a monospace typeface from ATK Studio.
Proto Mono™ is a modular monospaced font built with rounded shapes, designed with tech industrial taste by Radinal Riki. Created for electronic displays found in our modern techie world such as postal packing slips, airline tickets, informational video displays, ads, and more. Come with 2 styles with 4 weights each. This entire font is capitalized and with a character set that covers over 100 languages.
A1 features 1 website using Proto Mono. It leans towards Display font, Animated, and Typographic design styles, and it’s most often built with Control.