Here's the description of the Credit Card Tune-Up decision support tool from the site Credit Card Tune-Up: Maximize Your Cash Back Rewards (www.CreditCardTuneUp.com):
Credit Card Tune-Up: Maximize Your Cash Back Rewards
Choosing the best rewards credit cards to maximize your Cash Back can be daunting. There are hundreds of credit cards to choose from and their reward structures are a complex mix of tiers, limits, and categories. New credit cards come out all the time and the rewards structures of existing cards change as well.
The Credit Card Tune-Up tool makes all of that easy. Just plug in how much you spend each month, press Enter, and you'll be presented with a list of recommended cards sorted from best to worst by your expected annual reward. If having more than one credit card and using each card to its strengths could yield a greater annual reward, then each of the best N-card combinations is presented in columns labeled "Best N-Card Combo".