In banking, just like in dating, you want the person you're courting to be at ease.

With that in mind, Simple (formerly BankSimple) has launched a feature to let customers link their traditional bank accounts to the tech startup's service. More than anything else, account linking lets newcomers test the waters — fee-less-ly moving money in or out of their recently set up Simple accounts.

The service uses ACH transfers.

"You know, on a basic level, what you want is freedom to move your money around," says John Kim, the company's head of product. That flexibility might eventually enable a person to switch banks altogether, he adds.

"I think it is a basic step in getting your account set up, but it's also a path to make Simple your home and that's the ultimate goal."

Since last year when Simple launched in beta, customers got the chance to move a limited amount of cash in a one-time transaction from their old bank during the onboarding process along with always being able to set up direct deposit.

Eventually, the Portland tech startup, which relies on the Bancorp Bank to hold its customers' deposits, added remote deposit capture. The technology gave customers the chance to write a check themselves in order to move money.

Account linking, however, is a sea change for the company.

"We knew from the get-go that we would need this feature," says Kim. "Since our launch, one of the very first questions our customers were hitting us up on was: How do I transfer funds into Simple?"

At other banks such features cost cash, he adds.

"At several of the major banks, you can expect fees of up to $6 for outbound ACH funds transfer requests," Kim wrote in a company blog post. "One of the most interesting things we learned while building our ACH service: It costs banks just a fraction of a cent to send an ACH transfer."

Simple began working on account linking about six months ago with Bancorp.

"What [Bancorp] would have offered is their interface for managing ACH transfers and it would have required us to push our customers into an interface that wasn't completely controlled by us," says Kim. The Simple process gives the tech company more insight into the process and how the funds are delivered.