CodeJam is a great platform with interesting problems. But I think I'm not the only one who is annoyed because you can not filter all the participants from your country. That feature can help you to find your friends who are participating too, but you can find them if you know their username beforehand.
I have found a work-around solution for that.
- Copy this
Create a new bookmark on your browser with the above url.
Then visit CodeJam leaderboard page, e.g. 2020 CodeJam Qualification Round (you can do it even in incognito mode, if you are suspicious about the security).
When the page finished loading, click the bookmark you just added.
There will be a window — write the name of your country there e.g. ("Sweden", "Armenia", "India").
Open the browser console
F12— you'll see the list of participants from your country growing step by step.The list will gradually increase in size with more pages parsed. Look for familiar people :)
If you are happy at some point and don't want to continue, type
debuggerin the console, and freely explore the list.
An example of output: (for "India"). 
