Jason Gillikin explores the 7 tops cloud storage services. Smartphones and tablets constituted a full 7 percent of U.S. digital traffic in late 2011, according to market analysis firm comScore. If you use one or more of these portable computing devices, you need to stay connected with your files and settings, and cloud storage solutions help fill the bill. These services enable you to store files on the Web or sync files among several devices you own, over the Internet. As more Americans make more use of mobile devices, the market for cloud computing services will likely heat up.

1. Amazon Cloud Drive
• Amazon’s Cloud Drive permits the uploading of any file type, although it’s optimized for music files. The Cloud Drive syncs with Amazon’s retail operation so that any music purchased through Amazon.com filters to your computer by means of a download tool that’s linked to Cloud Drive. The service uses a Web interface primarily and doesn’t include sharing features.

Free space: 5GB
Maximum file size: 2GB
Paid tiers: $1/GB per year in increments of 20, 50, 100, 200, 500 or 1,000
Desktop apps: No
Mobile apps: Android, BlackBerry, Palm
Web access: Yes
Online Sharing: No

2. Apple iCloud
• Apple iCloud emphasizes the integration of apps and data, rather than folder syncing. An iCloud app integrates connected email, contacts, calendars and mobile apps across an account, for all devices associated with that account. Apple apps like Pages or Numbers sync natively with iCloud, as does iTunes, Books and Photo Stream. iCloud is intended to keep several iOS-based devices always in sync, including settings and media files.

Free space: 5GB (including email)
Maximum file size: N/A
Paid tiers: No
Desktop apps: No (Windows tool for data sync, however)
Mobile apps: iOS
Web access: Yes
Online Sharing: Yes

1. Box

• Box provides a robust consumer experience that emphasizes its collaboration tools. Individual files or folders turn into shared workspaces with task assignments, comments and discussion threads. The company provides three account tracks: personal, business and enterprise. Of the major cloud services, Box most aggressively recruits business clients with workflow-management tools and administrator accounts to manage many users at once.

Free space: 5GB
Maximum file size: 100MB (free account) to 1GB (50GB account)
Paid tiers: 25GB for $9.99/month, 50GB for $19.99/month
Desktop apps: No
Mobile apps: Android, BlackBerry, iOS
Web access: Yes
Online Sharing: Yes

4. Dropbox
• One of the original consumer cloud services, Dropbox differentiates itself through careful use of a user’s bandwidth. The desktop app includes user-specified limits so that large file transfers won’t clog up a slower Internet connection. Dropbox only syncs parts of a file that changed, making it a good choice for people with tightly metered bandwidth, like mobile hotspot users who can rack up significant overage fees.

Free space: 2GB (plus 500MB for every referred new sign-up, up to 18GB free in total)
Maximum file size: 2GB
Paid tiers: 50GB for $9.99/month or $99/year, 100GB for $19.99/month or $199/year and team plans of unlimited space at $795/year plus an additional $125/year for each user above the five-person base price
Desktop apps: Max OS X, Linux, Windows
Mobile apps: Android, BlackBerry, iOS
Web access: Yes
Online Sharing: Yes

5. Google Drive
• Google Drive, released in 2012, replaces the Google Docs tool. It builds on the Docs framework by including features like version history, which lets users review prior saved editions of any file — helpful when you need to “undo” past your last saved version. Google Drive integrates with Gmail and other Google products, including Android and the Chrome browser, to provide a seamless experience for people who rely on Google’s network of services.

Free space: 5GB
Maximum file size: 5GB
Paid tiers: Nine tiers, from 25GB at $2.49/month and 100GB at $4.99/month, to 16TB at $799.99/month
Desktop apps: Mac OS X, Windows
Mobile apps: Android, iOS
Web access: Yes
Online Sharing: Yes

6. Microsoft SkyDrive
• Microsoft SkyDrive received a significant overhaul in early 2012 to prepare the service for the autumn launch of Windows 8 and Windows Phone 8. SkyDrive syncs natively with Microsoft Office 2012, including the online version of apps like OneNote. The SkyDrive desktop app for Windows lets users remotely log into the computer using two-factor authentication (Windows Account login and password, plus a six-digit passcode sent to an enrolled cell phone) to access the file system — perfect for grabbing a file not already in the SkyDrive folders.

Free space: 7GB (25GB for accounts that existed before the 2012 upgrade)
Maximum file size: 2GB
Paid tiers: $10/year for 20GB, $25/year for 50GB, $50/year for 100GB
Desktop apps: Mac OS X, Windows
Mobile apps: iOS and Windows Phone 7, with Microsoft-approved third-party apps for Android
Web access: Yes
Online Sharing: yes

7. Ubuntu One
• Ubuntu One deeply integrates into Ubuntu Linux. This cloud solution includes special options for syncing contacts and notes (using the Tomboy program) within Ubuntu. Windows users aren’t left out: Ubuntu One includes a program for syncing a folder tree with the service. There’s no desktop app for Mac, but there’s a mobile app for iPhones and iPads, as well as Android. The mobile app supports music streaming, with a package that costs $3.99/month or $39.99/year for 20GB dedicated just to streaming your music selection.

Free space: 5GB
Maximum file size: 5TB
Paid tiers: $2.99/month or $29.99 per year for each additional 20GB
Desktop apps: Ubuntu Linux, Windows
Mobile apps: Android, iOS
Web access: Yes
Online Sharing: Yes