You have many options for a group fitness certification as the others have already mentioned, but I would make sure the certification you choose is nationally recognized and holds high standards.
As a side note suggestion, an NCCA accredited personal trainer certification would pair really well with a group instructor certification. An understanding of anatomy, physiology and how the body moves would be beneficial for the small group classes such as bootcamps that you wish to teach. It will give you a better understanding of the body.
Best wishes to you,