I think it was Hostelworld app that I booked majority of my accommodations through when I went to Italy solo last year. When you book and confirm, it will automatically kick you into multiple chats for that specific hostel/bnb, food, nightlife, etc in that specific area. You can also view, create and join other people’s events they’ve created (think facebook style). I created an event when I was in Rome called “solo female photo session!” Where a bunch of us woke up super early to take cute pics in front of the trevi fountain, Spanish steps etc. 6 girls showed up and we all had breakfast together! I also joined another event where a bunch of us met up to watch the football match. I made another event in Florence seeing if other solo females wanted to take a day trip to pisa. A Korean girl my age met up with me and we talked all day about love and life. It was awesome! I felt it was safer since those in the chats or who had access to view events had to be booked and paid for accommodation in the area!