Mondrian is the best code review tool I've ever used, but I'll admit that could be damning with faint praise... I'm very curious to hear what the better options

Mondrian is the best code review tool I've ever used, but I'll admit that could be damning with faint praise... I'm very curious to hear what the better options are, because we use Github at my current company and I would go back to Mondrian in a heartbeat.