<i>&quot;Let third parties manage the customer interaction.&quot;</i><p>Bad idea.  Dealing directly with a regulated bank, you know who to blame and have more legal protections. With some third-party intermediary, who pays for fraud?  App developers will try to wiggle out of taking any responsibility.  PayPal and WePay, for example, have routinely done that.<p>Read &quot;simple.com&quot;&#x27;s user contract.[1]<p>[1] <a href="https:&#x2F;&#x2F;www.simple.com&#x2F;policies&#x2F;bancorp-account-agreement" rel="nofollow">https:&#x2F;&#x2F;www.simple.com&#x2F;policies&#x2F;bancorp-account-agreement</a>