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.
David Beckham has played down reports that he could move to Monaco, but reiterated he is 'very flattered' by some of the options he has to consider.
The midfielder is leaving Los Angeles Galaxy after Saturday's MLS Cup final and French side Monaco are among several clubs from across the globe to have shown an interest.
The likes of Paris St Germain, Queens Park Rangers and West Ham United have also been linked with a swoop for the former Manchester United star.
Beckham remains confident he can still play at a competitive level as the 37-year-old weighs up where he will likely finish his playing career.
"I heard about Monaco on the way to training this morning from a friend in London who said 'I hear you are going to Monaco'. That was the first I'd heard of that," said Beckham.
"I've got some interesting and exciting options on the table.
"I am very flattered by some of the options that I've got. I still feel I can play and I'm not considering retiring.
"I've still got managers like Carlo Ancelotti and Harry Redknapp and Sam Allardyce coming out that are saying they'd love me to play and they know how professional I am, it means a lot to me.
"It is what I have tried to base my career around, over the years, being professional and working hard, so it's nice to be recognised like that.
"I do believe I still have got another challenge inside, that I can still play for, I don't know how many years left. I do still feel I can play."
Earlier Beckham hinted a return to England is unlikely.
He said: "I've always said I think I would struggle to come back and play in England because I've played for the biggest club in the world, the biggest club in England, Manchester United, and I couldn't see myself playing for any other Premiership team.
"But you never know. Like I said, we've got some exciting options on the table. I do think we'll be spending a little more time in England because it's good for the kids to see their grandparents.
"Over the last six years it's been difficult not seeing them as much as we'd like and they'd like, but we definitely won't be leaving LA for good."