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.
Dropbox - Online Sync and File Sharing
Reetro.io - Reetro is a versatile retrospective tool for agile teams, collaborate with your team and get better in what you do with a simple, intuitive and beautiful tool
Google Drive - Access and sync your files anywhere
Retrium - Sprint retrospectives made easy and effective for distributed scrum teams.
Mega - Secure File Storage and collaboration
FunRetro - Our fun, simple, and intuitive tool will revolutionize your teams collaboration process. Try it today for free and discover how fun retrospectives can help you.