There are no legal or functional extensions that can reveal a completely private Facebook friend list. Software claiming to do so is almost certainly a scam.
View the shared connections that users have explicitly chosen to keep public. Facebook Friend Mapper Extension Download
The was originally a Google Chrome extension designed to exploit a logical flaw in Facebook’s privacy settings. Its primary "feature" was the ability to reveal a user's hidden friends list, provided you had at least one mutual friend with that person. There are no legal or functional extensions that
: Executable files (.exe) or unpacked Chrome extensions (.zip) hiding malicious code. The was originally a Google Chrome extension designed
Go to the Facebook profile of the person whose hidden friends you want to see. You must have at least one mutual friend with them for the tool to work.
Shortly after the tool gained mainstream media attention, Facebook closed the API loophole and security vulnerability that allowed the scraper to function. Consequently, Google removed the extension from the Chrome Web Store for violating developer policies regarding data scraping and user privacy.
These tools often require you to be logged into Facebook, giving the extension developer access to personal data. Safe Alternatives for Managing Connections