The popularity of Dropbox free cloud storage has given opportunity for companies to start offering alternatives at competitive feature & prices (for pro). Below is a list of free cloud storage, a Dropbox alternatives you might want to try.

MEGA, The Privacy Company
- 50GB free cloud storage
- End-to-end Encryption
- Secure global access.
- Secure real time collaboration.
- paid membership stating $11.40 for upto 4TB
- http://mega.co.nz/

Copy
- 15GB free cloud storage
- Up to 5 users totally Free fair, shared storage
- Software for windows, linux , mac, android, ipad & iphone.
- paid membership starting $9.99/month for 250GB
- https://www1.copy.com/

MediaFire
- 50GB free cloud storage (starting 10GB)
- Software for windows, linux , mac, android, ipad & iphone.
- paid membership for as low as $2.49/month
- http://www.mediafire.com/

cCloud by Comodo
- Free cloud storage 10GB (personal) & 1GB (business with unlimited users)
- Secure storage, secure transmission. Works just like a local drive.
- For desktop, mobile and tablets.
- paid membership starting $7.99/month for 100GB (personal), $4.99/month for 50GB (business)
- https://www.ccloud.com

Box
- 10GB Free cloud storage
- Access through desktop, laptop, iPhone, iPad, Android phones and tablets
- paid membership starting $5/user/month for 100GB
- https://www.box.com/personal/

Windows Skydrive
- 7GB Free cloud storage
- Built-in feature at Windows 8.1
- For windows, mac, web and remote access.
- Real time collaboration, track versions.
- Free note taking apps for your phone.
- http://windows.microsoft.com/en-us/skydrive/download

Amazon CloudDrive
- 5GB free cloud storage.
- 50GB free when purchasing phones involved in the promotion: Samsung Galaxy S4, Samsung Galaxy Note 3, HTC One, LG G2,Motorola DROID MAXX, Nexus 5, Samsung Galaxy S III and the Samsung Galaxy Mega.
- Protect Your Files. Keep Your Files in Sync.
- Apps for phone, tablet, and desktop (PC and Mac)
- http://www.amazon.com/gp/feature.html/ref=cd_nav_desk?ie=UTF8&docId=1000796781

iDrive
- 5GB free cloud storage
- Multiple Device Backup: PCs, Macs, iPhones, iPads and Android devices.
- Real Time Backup: Automatically recognizes the modified parts of files and backs them up in real-time.
- Facebook backup: Now you can easily backup Facebook photos and videos uploaded by you or tagged by your friends.
- Sub-accounts: Create multiple accounts using your storage space and monitor backups from a single administrator console
- Super Secure Transfer and store your files with 256-bit AES encryption using a user-defined key that is not stored anywhere on the servers.
- IDrive Express™ Quick backup and retrieval of your data up to 1 TB in less than a week via physical storage shipment, ensuring no bandwidth usage.
- https://www.idrive.com

Wuala by Lacie
- 5GB free secure cloud storage
- Client-side encryption: Uses AES- 256 for encryption, RSA 2048 for signatures and for key exchange when sharing folders, and SHA-256 for integrity checks.
- File sync software for windows, linux , mac, android, ipad & iphone.
- http://www.wuala.com/en/

One Ubuntu
- 5GB free cloud storage
- File sync software for windows, linux , mac, android, ipad & iphone.
- Add-on: 20gb for $2.99/month
- http://one.ubuntu.com