Founders Nation - Find or become a startup cofounder
PenPal World - Connect with people all over the world
CoFoundersLab - Meet 250,000+ entrepreneurs online
Unbordered - Unbordered app comes up with features to help you in finding the perfect language practice and exchange partners so you can practice foreign languages right through your mobile phone.
Co-founder Question Cards - Questions to ask your co-founder to know each other better.
We3 - AI that finds you the most compatible people nearby