For hosting common files it's ok. Also it is on Android too do, great to transfer files between your Windows and your phone. But if you want better security you have to subscribe a monthly offer.
Telegram - Telegram is a messaging app with a focus on speed and security. It’s superfast, simple and free.
Dropbox - Online Sync and File Sharing
WhatsApp - WhatsApp Messenger: More than 1 billion people in over 180 countries use WhatsApp to stay in touch with friends and family, anytime and anywhere.
Google Drive - Access and sync your files anywhere
Signal - Fast, simple & secure messaging. Privacy that fits in your pocket.
Mega - Secure File Storage and collaboration