A number of mobile apps allow users to track gas prices in their areas, as of March 2015. Some examples are GasBuddy, SmartFuel and Gas Cubby.
GasBuddy is free to use but relies on user data for gas price updates. It is available for iOS and Android.
SmartFuel offers an initial free-trial period, but requires a payment of $2.99 to continue using at the end of that period. Gas prices are drawn from national databases rather than user submissions.
Gas Cubby can be used for free with ads displayed, and users have the option of paying $2.99 to remove the ads. It is available for iOS and is optimized for the iPhone 5.