A technology startup in San Diego has just raised $30 million from investors to continue building out its software for cashier-less, "grab-and-go" stores. The model, popularized by Amazon Go, allows shoppers to simply walk into a store, grab items from the shelves and walk out — with the receipt sent directly to their mobile device.

The startup, Accel Robotics, is developing computer vision software — along with cameras, sensors and store equipment — to make this concept work. In fact, the startup can build out an entire modular store for its customers, preloaded with the computer brains to enable a "checkout-free" experience.

The new money came in a round led by Japanese funding giant SoftBank, with further participation from New Ground Ventures, Toyo Kanetsu Corporate Venture Investment Partnership and RevTech Ventures.

Co-founder and CEO Brandon Maseda said Accel Robotics already has its technology deployed in North America and Japan, including at restaurants and drugstore chains. However, Maseda was slim on specifics, saying he couldn't reveal who his customers were just yet. Broadly, the company plans to create stores from scratch — and partner with existing retailers — to help bring small-format stores to locations that couldn't accommodate larger buildings. Think university campuses, corporate offices and office parks, military bases, airports and other travel hubs.

"The idea is to deliver small, modular stores closer to where people live and work," Maseda said.

Accel has a lot of competition in the world of grab-and-go retail tech.

Technology titan Amazon announced big ambitions for the cashier-less store model, with plans to expand to larger formats and license the technology out to other retailers. Amazon is joined by a slew of startups looking to create cashier-less checkout systems.

How will Accel compete? Maseda said they've kept their heads down, focusing on building a product instead of getting caught up in the media hype around cashier-less stores.

"We've been focusing on building the world's most convenient cashier-less store. If we get that right, then the rest will take care of itself," he said.