But the secret may be out if the recipe one Georgia man claims to have accidentally found is truly the formula.
Cliff Kluge, from Ringgold, Ga., was searching through antiques with his wife when they purchased a box of letters at an estate sale, according to WXIA in Atlanta.
One of the papers Kluge found is a cola recipe from 1943 that Kluge says he believes is the original recipe for Coca-Cola.
"You don't stumble on things like this very often," Kluge said. "It's a letter, and a formula, and the processes to make it. I think it's a little deeper than having fun; I think it's the recipe for Coca-Cola."
Coca-Cola officials have not yet called Kluge back, but assured in a statement that the only real recipe is kept in the vault.
For now, Kluge has listed the recipe on eBay for a starting bid of $5 million.