When smart phones first took off, many software companies figured people might want to view files on the small screens, but few thought anyone would use them for creating, editing, and commenting on documents, spreadsheets, and presentations. “We were proven wrong,” says Raju Vegesna of Zoho, a company that offers online office tools.

Businesses are demanding things like spreadsheet and document editing tools that work anywhere, on any device. In response, large and small companies are now providing cloud-based office-productivity applications for smart phones and tablets.

It takes creativity to make them work. Web-based word processors such as Google Docs weren’t initially able to process touch-screen input. Google had to rework Docs so that it was possible to edit from certain devices, such as those running recent versions of Android. Zoho is building apps for mobile devices to bridge that gap for its products, enabling those programs to interpret users’ touch-screen “clicks.” Meanwhile, IBM is testing software that can break up large spreadsheets into portions for different users, making them less unwieldy to update and edit on tablets.

Cloud-based office software has been around for several years, making shared editing easier because multiple users need only keep track of one file. But the cloud is even more important when people are working on mobile devices, which are switched or replaced far more often than are desk-bound PCs.

The cloud is the natural central storage site not only for the data but for the productivity applications themselves, says Rick ­Treitman, entrepreneur in residence at Adobe and director of product marketing for its Acrobat.com cloud-based office applications. Zoho’s Vegesna notes that users expect custom apps tailored to the iPhone, the Android tablet, or whatever device they’re working on.

Scott Johnston, group product manager for Google Docs and Sites, says that while the interfaces will look different on phones, tablets, and PCs, “I suspect we’re going full-featured on every device.” He believes that workers will eventually use tablets in place of laptops and demand productivity software that works just as well on them. Potential advances in touch-screen technology—such as ways to give users more tactile feedback—could also accelerate demand for such apps.

While Google offers primarily cloud-based apps with light offline capabilities, Microsoft recently launched a cloud-based version of its Office productivity software called Office 365, betting that users will see advantages in full-featured offline software that also allows for accessibility in the cloud. Microsoft reasons that people want more features than most cloud apps offer, and want to be able to work when network access is unavailable.