A start-up company called Collaborall is offering a free online tool for sharing and editing spreadsheets created in Microsoft Excel.

While online tools such as Google Docs & Spreadsheets solve the problem of how to keep track of different versions of spreadsheets and word processor files, Collaborall’s Xcellery program lets users share and edit spreadsheets online using Microsoft Excel itself, eliminating the need for users to learn a new program.

“It takes Microsoft Excel and makes it multi-user-friendly,” says Reto Laemmler, a software engineer in San Francisco who is the founder and sole employee of Collaborall. “All the changes people [make in Excel files] are immediately reflected to the team. People can work at the same time.”

A beta version of the product was released in May. About 3,000 people have subscribed to the free online service, while about five companies are using a paid version that is only available as an add-on to Salesforce.com and has benefits, including extra storage capacity, according to Laemmler.

LeaderTreks, an Illinois-based group that organizes youth trips, training and curriculum to train future church leaders, began using Xcellery last fall as an add-on application to Salesforce.com’s hosted CRM software.

LeaderTreks was using Excel calendars to schedule trips, but only one person could work in a document at a given time. This created problems when two employees were selling trips simultaneously. Also, if someone was telecommuting, that person had to call the office to find out whether a spot on the booking calendar was available.