What are some great photo editing apps?

So i follow a lot of famous people like kendall and kylie jenner, As well as beauty guru's on youtube. And i know they have Iphones, but all of their instagram pictures look really beachy and the lighting is amazing. I really wanna know what app they use that makes their pictures have that southern california look.

Http://pookeeboo.blogspot.com/p/image-edit.html#sthash.ckzHlBxY.dpbs