Ftopia offers 5 GB free storage.

Features of Ftopia:
- 5 GB Total Storage
- Up to 10 users
- 3 Rooms
- Simple Sharing
- Free Native Apps
- Custom Branding
- 1 Public Room
Source: Ftopia
They also offer an Android and iOS app for Ftopia.
52 Free Online Backup Services | Updated August 2018
Moren than 1,5 GB free storage space in the cloud