The best alternatives to BlabRoulette are Hello, A Random Casey Neistat Vlog, and WeKiki. If these 3 options don't work for you, we've listed a few more alternatives below.
Macarons is your virtual watercooler for casual conversations with colleagues you rarely meet on the hallway. Just add the Macarons app to a Slack channel and it will automatically pair off random members for having a casual chat over coffee.