Est. 2011, Rancho Santa Margarita, CA
Number of locations: 98
What makes it unique: Two words: unlimited toppings. Pieology isn't the only one on the list with that promise, but its topping arsenal boasts 78 billion possible pizza outcomes based on combinations of crusts (white, wheat, gluten-free), sauces (house red, alfredo, herb butter, pesto), the usual meat/cheese/veggie suspects, and "after bakes" sauces like fiery Buffalo or BBQ.
Why it might blow up: Designing your own pie is nothing revolutionary, but the fun factor in unleashing unlimited toppings while walking down a Chipotle-esque ordering line is a combination for success, as evidenced by the chain's explosive growth of 32 new locations in California alone during 2015. Plus, it recently received an investment from Panda Express.