I've resorted to writing a service that can initiate transfers and retrieve transactions for a smaller US bank.

I really just want a bank account with an API, that would be so, so nice.

That was the promise with Simple (which they promptly abandoned), it's the main reason I signed up with them in the first place.

You can get away with something like Plaid if you just want data but for actually making moves you'd need something else.

I know Chase at least offers an OFX endpoint if you pay a monthly fee (like ~$10/mo). I wrote a tool a while back that would automatically use that to download my transaction data and store it in a local format for personal accounting purposes. It worked well, but I abandoned it out of laziness.