Telegram Messenger lets users send text messages, stickers, images, videos, and other files to one or many people for free, all using encryption to keep one-to-one messages secure and private, though some security experts question the quality of the encryption. The software is open-source as well, so savvy users can see exactly how information is collected, stored, transmitted, and secured. As with Snapchat, private-messaging sessions can be created between users with preset self-destruct timers; secret messages aren't stored on the app's servers. After six months without use, accounts also self-destruct. Setting up a username allows other users to find you, but a username isn't required. How much questionable content is available through the app is entirely up to users and their contacts, though the open-source nature of the platform means anyone can create stickers, bots, and plug-ins, many of which feature decidedly adult content. As such, it's really only appropriate for older teens to use to communicate with family and trusted friends.