Recent changes to the discord api essentially rendered this tool incapable of fetching needed data, hence the reason for archiving the repo.
Get the list of people that you have shared servers with. And it works for all users, not just friends.
Note: It's not a nodejs module, as you might expect, it's just a set of few scripts. However if you want to make it a module, please do, any contributions are welcomed!
Repo consists of 3 different scripts.
$ cd discord-global-mutual
$ npm install
$ node export.js [YOUR_DISCORD_USER_AUTH_TOKEN]
$ node compare.js
$ node print.js > output.txt
To get Discord user auth token, you can just get the one, that is used in your browser/discord client. Open Chrome Dev Tools -> Network tab, find any Discord API request, click on it, scroll to Request Headers, and there it is, the "authorization" header. Just copy the value and use it ;)