One of Shake Shack's competitors is experiencing major growth

One of Shake Shack's competitors is climbing to the top of the fast-casual burger sector.

BurgerFi is one of the fastest-growing burger franchises in the country.

The chain began in 2010 as a spin-off of a swanky restaurant in Delray Beach, Florida called The Office. 

The Office is a high-end American pub, but the founder noticed that two burgers comprised 60% of its sales.

John Rosatti, the CEO of The Office, decided to create a burger joint inspired by these two top-selling burgers. 

BurgerFi opened its first location in Delray Beach, Florida in 2011. It initially intended to serve organic burgers. 

But it needed to stand out from the competition and also appeal to customers.

The restaurant's beef is free-range, with no added chemicals or steroids.

Its slogan is, "from the farm, not the lab."

In keeping with its all-natural theme, each location's furnishings are made sustainably. The chain's chairs are made out of upcycled Coca-Cola bottles, and its tables are constructed out of upcycled milk jugs.

"We wanted to create a feel-good environment in all aspects," BurgerFi's global brand ambassador, Steve Lieber, told Business Insider. "So as a whole, it's a natural food and natural design restaurant."

BurgerFi is experiencing major growth. It will have 81 locations in the United States and two locations in Mexico by the end of the year. The chain plans to expand internationally in Panama and the United Kingdom.

The chain looks to its competition for inspiration. 

"We wanted to expand on what Shake Shack is doing, by offering more while keeping it simple," Lieber said. 

Customers can choose from six different types of burgers, including a gluten-free and vegetarian option. The restaurant also offers hot dogs, French fries, onion rings, and custard. 

 The gluten-free lettuce wrap burger option.