The J's Crab Shack app is here and it's the best way to net some big savings on high-quality seafood without having to drive to the shore! Just one bite and you'll be hooked, discovering for yourself why they say J's Crab Shack is "Where the portions are bigger and the fish is fresher! ". The J's Crab Shack app provides: Loyalty Program. Menus. Photos. Event Information.