FORT COLLINS - OtterBox LLC in Fort Collins and Boulder-based firms Rally Software Development Corp. (NYSE: RALY) and SendGrid Inc. are among five organizations that will host the Go Code Colorado Challenge Weekend.

The challenge in Fort Collins will be held at OtterBox's headquarters, 209 S. Meldrum St., while the challenge in Boulder will occur at Rally's headquarters, 3333 Walnut St. SendGrid will host the challenge at its office in Denver, 1451 Larimer St.

The event begins at 6 p.m., Friday, March 21, and will continue through Sunday evening, March 23.

More than 100 programmers and tech geeks will gather at five locations across the state to see if they can develop apps that will make the Colorado Secretary of State's Office more user-friendly to businesses. In addition to the sites in Boulder, Fort Collins and Denver, programmers will compete at EpiCentral Coworking in Colorado Springs and Durango Space in Durango.

Sponsored by Google, the event has attracted more than a dozen regional sponsors, including OtterBox and Rally.

"For a whole new idea, we're optimistic about turnout," said Andrew Cole, a spokesman for the secretary of state's office. "We've had good enthusiasm up to this point."

Two teams of finalists will be selected from each region and will go on to a final competition May 9. The challenge is open to individuals. Three winners will be selected and will receive up to $50,000 in cash and in-kind incentives, Cole said. The project is a bi-partisan effort of the Governor's Office of information Technology, the Colorado Office of Economic Development and International Trade, the Statewide Internet Portal Authority and the secretary of state.