An analysis of airline fees by Travelnerd, a website that offers airport parking info, terminal maps, airport shuttle directories and other ways to ease traveler's airport navigation, found that more than 50 airline fees changes in the last year. Of the fee changes, 36 out of the 52 were direct fee increases. Eighteen out the 52 fee changes were attributed to Spirit Airlines and Allegiant Air, "ultra low cost carriers notorious for charging fees" according to the report.  

According to the online report: "These changes have had a tremendous impact on U.S. travelers, especially on families. Travelers really have to be extra cautious when booking a flight. U.S. carriers are becoming creative at charging consumers extra fees,” says Alicia Jao, VP Travel Media at TravelNerd. “A new trend that we’re currently seeing is carriers bundling and tiering services. This practice is not only more confusing for travelers, but it also complicates price comparison. Even airlines that have touted fewer fees are joining the game, indicating only more fees in 2013."

Fees are becoming an increasingly heated topic among travelers, and online sites are trying their best to keep track. is one of them. Go here to download a PDF of "every airline fee you'd want to know about."