Mattermost - Mattermost is an open source alternative to Slack.
TripCost - Travel like a local
Telegram - Telegram is a messaging app with a focus on speed and security. It’s superfast, simple and free.
WKND - Easily create personalized local weekend adventures
Slack - A messaging app for teams who see through the Earth!
2B LOCAL - Social travel & lifestyle app with tips by friends & locals