GasBuddy is the king of "find cheap gas" apps, with an 11-year history and a user base of 5 million. The app uses a points system and a weekly $250 gas card giveaway to entice users to post their local station's prices. It works.
Each submission is timestamped, and prices are listed for various fuel grades. GasBuddy organizes the data into heat maps and lists, and visitors can search by zip code to find the cheapest nearby gallon. Prices are available for all 50 states and D.C., as well as Canadian provinces.
"In most cities across the country, it's easy to save 20 to 30 cents a gallon," says GasBuddy co-founder Jason Toews. "That's real savings. You just need to know where to go."