Hypur, a two-year-old company based in Arizona, has built software for banks that uses GPS to geo-locate each purchase and prove it was done in an authorized dispensary.

That has been enough to allow Hypur to raise more than $5 million from investors.

The California-based start-up Kind Financial is offering software as well as hardware, in the form of kiosks that can go inside dispensaries. Customers can deposit cash in the Kind kiosk to pay for their purchase, removing one headache for the dispensary.

Mr. Zarrad’s start-up, Tokken, is younger than the others, but he is aiming to offer something new — an electronic payment system that will not rely on the credit card companies or debit networks. Somewhat like PayPal or Venmo, Tokken will use the electronic money transfer system in the United States known as the Automated Clearinghouse, or ACH, to move money from the bank account of a dispensary customer to Tokken’s bank account. Tokken will then keep subaccounts for each dispensary — making it unnecessary for the banks to deal directly with dispensaries.

Mr. Zarrad is confident he can stay on the good side of the banks because of his experience as a regulator, and before that, in the financial industry.

Mr. Zarrad, 36, briefly worked as a financial adviser for Merrill Lynch after serving in the Marine Corp for six years. He took the job with the O.C.C., which regulates all national banks, in part because he spotted the opportunity in marijuana compliance and wanted to understand the financial system better.

In his nearly two years with the O.C.C., Mr. Zarrad was often on the road, combing through the books of regulated banks. He said that his teams would not crack down on banks if they were openly working with marijuana businesses, as long as they were tracking the transactions carefully.