download:
bitchat.free
ios: https://apps.apple.com/us/app/bitchat-mesh/id6748219622
android: https://play.google.com/store/apps/details?id=com.bitchat.droid

github:
ios: https://github.com/permissionlesstech/bitchat
android: https://github.com/permissionlesstech/bitchat-android