(Reuters) -OpenAI on Monday introduced a feature that would allow users to make purchases through ChatGPT, in partnership with Etsy ( ETSY ) and Shopify ( SHOP ).

Merchants will have to pay a fee on completed purchases to OpenAI, and it doesn't affect their prices. There will be no charges for the Instant Checkout for users.

The move opens up a new source of revenue for OpenAI, taking advantage of the heavy user traffic on ChatGPT, in addition to its traditional subscription model.

"U.S. ChatGPT Plus, Pro, and free users can now buy directly from U.S. Etsy ( ETSY ) sellers right in chat, with over a million Shopify ( SHOP ) merchants, like Glossier, SKIMS, Spanx and Vuori, coming soon," OpenAI said in a blog post.

Starting Monday, Instant Checkout will support single-item purchases, but OpenAI said it will add multi-item carts and expand merchants and regions.

Shares of Etsy ( ETSY ) rose 7.3%, while U.S.-listed shares of Shopify ( SHOP ) popped 4.5% after the announcement.

"Shopify ( SHOP ) merchants will be able to sell directly through ChatGPT conversations - no links or no redirects, just seamless commerce," the platform said on its website.

Etsy's ( ETSY ) chief product and technology officer, Rafe Colburn, said that AI-powered and agentic shopping presents meaningful opportunities for the online marketplace.

Colburn said that Etsy ( ETSY ) is working with a tech partner - without naming the company - to seamlessly integrate product discovery into mobile experiences.

OpenAI said it will open-source the agentic commerce protocol, built with payments firm Stripe, which powers the checkout.