Cardiff will allow long-serving Kevin McNaughton to leave this summer along with Danny Gabbidon and Nicky Maynard.
Highly-rated Atletico Madrid midfielder Saul Niguez has signed a new five-year contract.
Rangers have confirmed the departure of defensive duo Carlos Bocanegra and Dorin Goian after their contracts were mutually ended.
United States international Bocanegra spent last season on loan at Racing Santander while Goian played for Spezia in Italy's Serie B, as the Ibrox side looked to reduce their wage bill following relegation to the Irn Bru Third Division.
A statement on the club's website said Bocanegra, 34, is expected to move back to his homeland to join a Major League Soccer club, with 32-year-old Romanian Goian looking for a side in England.
"After discussions in the last few days, both men are now free to pursue their careers elsewhere having terminated their deals in Glasgow a year early," the statement read.
Former Gers captain Bocanegra made 40 appearances for the club, scoring three times.
Goian turned out 41 times in a Rangers shirt, with his only goal in the 3-2 League Cup defeat to Falkirk in 2011.