In addition to Shopify, chatbots have come out over the past 12 months from Instacart, the delivery company; Mercari, a resale platform; Carrefour, a retailer; and Kering, which owns Gucci and Balenciaga. Walmart, Mastercard and Signet Jewelers are also testing chatbots, which may become publicly available as soon as next year.

“In a way, it’s recreating an in-store environment, but online,” said Carl Rivera, a vice president at Shopify who oversees its Shop app, which hosts Shop A.I. He said the chatbot broke down people’s questions into key terms and searched relevant products from Shopify’s millions of sellers. It then recommends products based on reviews and a shopper’s purchase history.

Retailers have long used chatbots, but previous versions lacked conversational power and typically answered just a few preset questions, such as the status of an order. The newest chatbots, by contrast, can process prompts and generate tailored answers, both of which create a more “personalized and authentic interaction,” said Jen Jones, the chief marketing officer of the platform Commercetools.

Whether shoppers want this technology remains a question. “Consumers like simplicity, so they don’t necessarily want to have five different generative A.I. tools that they would use for different purposes,” said Olivier Toubia, a marketing professor at Columbia Business School.

Nicola Conway, a lawyer in London, tried Kering’s luxury personal shopper, Madeline, in August to search for a pink bridesmaid dress for a spring wedding. Madeline was “intuitive and novel,” she said, but it gave only one recommendation, an Alexander McQueen corset dress. Ms. Conway did not end up buying it.