Brighton have offered new deals to Casper Ankergren and Inigo Calderon but club-record signing Craig Mackail-Smith will be released in the summer.
Right-back Calderon, 33, has played 39 times this season, while goalkeeper Ankergren, 35, has only featured once.
Striker Mackail-Smith, 31, joined for a reported £2.5m in 2011 and has scored three goals in 35 outings this season.
Kemy Agustien, Aaron Hughes, Vitalijs Maksimenko and Paddy McCourt will also leave when the season finishes.
"It's always difficult because you have to make decisions and try to look to the future and anticipate where you can strengthen," Brighton manager Chris Hughton told BBC Sussex.
"For those that receive new contracts, it is because it is in the best interests of the club and generally they have deserved it.
"For the ones who don't, it gives them an opportunity to be somewhere where possibly their fortunes may change and they may play the regular football that all players want to do."
Mackail-Smith scored 10 goals in 50 games during his first season at Brighton after moving to Sussex from Peterborough.
The Scotland international had a better strike-rate in his second season, but suffered a serious Achilles injury in March 2013 which kept him out for more than a year.
He has not scored since last September, a spell which included a three-game stint back on loan with Posh.
Ankergren and Calderon were part of Brighton's League One-winning side in 2011, with Calderon the club's longest-serving player.
"Casper has been our third-choice goalkeeper and that can be quite a specific role," Hughton added.
"With Calderon comes a package. He is a team player, is popular and has a versatility in his game."