Short answer: No monthly fees on the free plan; Kronos Pro is $9.99/mo.
Free plan: no monthly fee, no overdraft fee, no minimum-balance fee, no transfer fee. Crypto on free tier pays only the network fee (clearly disclosed before each trade). Kronos Pro is $9.99/month and unlocks 2.5% APY savings, $0 crypto fees, boosted cashback, priority support, and unlimited P2P transfers.