The Citi Custom Cash is a super flexible cash-back earning card with the ability to earn 5% back on your top (eligible) spending category. This holds true for up to $500 spent each billing cycle, then 1% back after that. This flexibility means no sign-up is required for rotating categories. As your top spending habits change, so will your 5% earnings. It's truly a no-fuss card that gives you high-earning rates with really no work required. Just keep in mind this card does have foreign transaction fees.