Michael Brown, Danny Webber and Richard Hughes head a 10-strong list of players released by Portsmouth.
Former Tottenham and Sheffield United midfielder Brown has not played for Pompey since Boxing Day due to a clause in his contract which would have triggered a new deal, crucially, on wages the club could not afford had he made one more appearance.
Fellow midfielder Hughes has also been let go due to a similar clause which prevented manager Steve Cotterill from playing him in another game for the Championship club, with his final appearance also coming in late December.
Talks broke down between the pair and Portsmouth in January when a financial compromise was unable to be reached despite the club's desire to keep them on board. Both players now leave Fratton Park on free transfers.
Striker Webber has been informed he will not be getting a new deal after recently returning from a serious knee injury.
Goalkeeper Darryl Flahavan and youngsters Marlon Pack, Pete Gregory, Tom Kilbey, Perry Ryan, Ellis Martin and Billy Goddard have also been allowed to leave Fratton Park.