Other members of the reigning World Series champions receiving offers before Tuesday's deadline are outfielder Gregor Blanco, outfielder/first baseman Travis Ishikawa, right-hander Yusmeiro Petit and catcher Hector Sanchez.
Belt returned from a concussion to help the Giants during the franchise's third championship run in five years. Sanchez's season ended prematurely because of a concussion.
Manager Bruce Bochy has said Petit - a talented starter and long man - might remain in the bullpen to begin next season because of his versatility. Petit set a major league record last season by retiring 46 consecutive batters over eight appearances from July 22 to Aug. 28.