Charleston-based software company Blackbaud is buying a Virginia-based database management firm for $17.5 million.

Blackbaud said in a news release today that it is buying Public Interest Data Inc. of Alexandria, Va. Public Interest Data also provides acquisition list services and data analysis for nonprofit organizations.

Blackbaud provides software and other services for nonprofit groups.

The deal was announced after the market closed today. Blackbaud shares were up 46 cents at $26.75 today, near its 52-week high of $28.73.

The company says it is paying for the deal out of cash on hand and the value could be up to $2.5 million more based on the performance of the acquired business over the next two years.