'Interview street':https://www.interviewstreet.com/challenges/ e un site ce organizeaza din cand in cand concursuri de programare care sunt folosite de mai multe companii pentru recrutare.
Companii cu siteuri de probleme:

'Asana': http://asana.com/challenge/
'Greplin': http://challenge.greplin.com/
'Justintv': http://jtvproblems.weebly.com/
'DropBox': http://www.dropbox.com/jobs/challenges
'ITA': http://www.itasoftware.com/careers/work-at-ita/hiring-puzzles.html
'Quora': http://www.quora.com/challenges
'Spotify': http://www.spotify.com/us/jobs/tech/
'Facebook': https://www.facebook.com/careers/puzzles.php
'RapLeaf': https://www.rapleaf.com/careers/challenges

'Asana':http://asana.com/challenge/
'Greplin':http://challenge.greplin.com/
'Justintv':http://jtvproblems.weebly.com/
'DropBox':http://www.dropbox.com/jobs/challenges
'ITA':http://www.itasoftware.com/careers/work-at-ita/hiring-puzzles.html
'Quora':http://www.quora.com/challenges
'Spotify':http://www.spotify.com/us/jobs/tech/
'Facebook':https://www.facebook.com/careers/puzzles.php
'RapLeaf':https://www.rapleaf.com/careers/challenges