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.
Slack - A messaging app for teams who see through the Earth!
Dropbox - Online Sync and File Sharing
Confluence - Confluence is content collaboration software that changes how modern teams work
Google Drive - Access and sync your files anywhere
Flock - A faster way for your team to communicate
Mega - Secure File Storage and collaboration