Ask HN: what US bank do you usually use for your startup?

Use a regional bank. Most have no fees for business checking accounts. I use Frost Bank - http://frostbank.com . They have iPhone deposits, decent online banking and I haven't paid them a dime in 8 years.

I asked the bank rep about if they open up their backend API for payout processing. Most came back to me with '??'. lol. what exactly should I ask them?

Do banks have their API open for us to do payout?

oh yeah, from my investigation, I found that wells fargo has the best fee, 0 fee if i have checking and savings acc and do monthly transfer between them.

I like Chase. Their online/mobile tools are great.

citi is decent. their backend looks like it was developed in the 70's, but it works