+1 for Balance
I've got a credit card and a debit/checking account, too.
As for Balance, I entered my debit/checking balance as the 1st deposit (new paychecks are entered as deposits, of course), then I use my credit card for purchases that I subtract as withdrawals. This way I don't spend more than I have in my debit/checking and I already take into account the money I need to pay off the bill at the end of the month.
I've got reward points on my credit card and I pay off my credit card bill at the end of the month, so I don't have any interest charges. If your card has reward incentives that are free to sign up, go for it. It can add up to buy holiday gifts for others or a nice birthday gift for yourself. But it only works well if you pay off your entire bill every month or else the interest charges will negate the benefits of the rewards.
I'm sure there are other money management apps that can use multiple accounts, but Balance is enough for me, it's easy to use and it's free.