"First and foremost, the Browns would like to thank Brandon and his agent for being true professionals," general manager Ray Farmer said in a statement. "The circumstances in which he found himself were not easy for him or the team. After discussions with Brandon and his agent, we'd like to give him the ability to pursue other opportunities."
Weeden was a surprise first-round pick by Mike Holmgren in the 2012 draft. Holmgren was so eager to find a quarterback he took Weeden in the first round at the age of 28, figuring if he got five years from him it was more than he'd gotten from many other players.
However, although he has a strong arm, Weeden possesses little mobility and a tendency to focus on one receiver when pressured. He also was caught in a maelstrom of negativity in Cleveland that included changes in ownership, front office and (twice) coaching staffs.
Weeden started immediately as a rookie, replacing Colt McCoy, and had a horrible first game (four interceptions, 34 percent completion rate). But Weeden bounced back to throw for nine touchdowns against six interceptions over the next seven games.
He regressed the rest of his rookie season and appeared headed out of Cleveland when Rob Chudzinski replaced Pat Shurmur as coach. But the team could find no better quarterback options and gave him the starting job in 2013.
Weeden knew the front office did not back him fully, but he had a desire to prove himself. It didn't go well -- he played in eight games, completed just 52.8 percent of his passes and lost all five of his starts.
He also became a lightning rod for fans frustrated with his play and the Browns' struggles.
Campbell, in his only season with Cleveland, passed for 2,015 yards, 11 touchdowns and eight interceptions.
"We appreciate Jason's contributions to the Browns in 2013," Farmer said in the statement. "He's a respected veteran player in this league. We felt like at this time, early in the free-agency period, we would give him a better opportunity to move forward. We wish Jason the best in his future endeavors."
Information from ESPN.com Browns reporter Pat McManamon was used in this report.