MonsterMarket

Monstermarket.io is a third party splinterlands marketplace and it's the only website which i use to trade splinterlands cards because it's easy to use and you get dec cashback from all of your purchases. They have advanced filters to find what you want and other then that they have lots of useful tools to calculate decks, rewards etc. Another useful feature is palying readymade splinterlands account on a profit sharing basis . I haven't tried this feature yet cuz there weren't any account available.
image source