One year ago Saturday, Amazon announced it would take over Whole Foods in a $13.7 billion deal that shook the grocery industry.

Since then, a number of e-commerce start-ups have scored paydays from big retailers. Walmart bought Flipkart, Target acquired Shipt, and Kroger invested in Ocado, for example.

But there's been another surprising beneficiary in the tech world: Google.

In the last year, the search giant has become an increasingly attractive partner for retailers looking for ways to compete with Amazon, allowing it to explore new business models and alliances.

For example, Target, Walmart, Costco and others all agreed to a new advertising program with Google that makes their products appear in search and through its smart, voice-activated Assistant at the same time, with a universal shopping cart that routes purchases through its Express shopping delivery service. Instead of paying for an ad, the retailers now have to give Google a cut of each purchase. It's an interesting new model for Google and helps retailers stay on par with Amazon by giving consumers a simple, consistent purchasing process.

And earlier in June, the search giant announced a fresh partnership with French supermarket giant Carrefour to sell its groceries through Google's shopping site and Home smart speaker.

For retailers, partnering with Google on shopping offers visibility and consumer convenience. For Google, its shopping service is crucial in helping it win back product searches from Amazon and stay relevant in the voice-powered future of e-commerce.