Random User-Agent is an open-source MIT-licensed browser extension that is designed to replace the original browser User-Agent identifier (is a sort of "fingerprint") with a randomized (based on your preferences). The extension is incredibly lightweight, using very few resources.
https://github.com/tarampampam/random-user-agent
Random User-Agent (Switcher)
(also on Firefox)
https://chrome.google.com/webstore/detail/random-user-agent-switche/einpaelgookohagofgnnkcfjbkkgepnp