Party with a Local - Party with a Local is a free app that connects travelers with locals that want to party.
Postcrossing - A postcard exchange project that invites everyone to send and receive postcards from random places in the world. For free!
Project Fixup - Meet people, not profiles
swap-bot - Swap-bot is a online service that organizes group swaps and a community of creative individuals.
Palaround - Meet people you should be friends with.
Random PenPals - Get a quarantine PenPal in 10 seconds