The Internet has “buy button” fever. This year Pinterest, Twitter, Facebook and YouTube have all made their sites and apps shop-able with the addition of buy buttons. It makes sense in a mobile-first world: You’re more likely to shop directly inside the app you’re already using than if you’re sent to a new site or different app.

Pinterest announced a large expansion of its “buy button” program today at the Digital Summit in Philadelphia.

Now, any commerce company which uses software from IBM Commerce, Magento and Bigcommerce, can utilize Pinterest’s buy buttons. Previously the company announced integrations with Shopify and Demandware, as well as direct retailers including Macy’s and Nordstrom. New direct integrations include Wayfair and Bloomingdale’s.

Moreso than other social networks, Pinterest’s users come to the service with a desire to purchase the things they find. That means pins from brands and commerce sites fit in with user-generated content. But the site’s many “pins” often link out to blog posts, or products that are no longer for sale. That’s why increasing the number of shoppable pins is part of Pinterest’s big challenge.

“What you need to power a great discovery service is lots of inventory,” says Michael Yamartino, Pinterest’s head of commerce. “By getting more merchants and more buyable pins and more products on the platform, we’re able to build smarter and better recommendations and search.”

The company has made progress there. Since launching its buy button for iOS devices in June, the number of pins which link to items for sale has doubled to 60 million. The company says that early results show the buyable pins are “more than doubling” the rate at which shoppers convert into buyers, compared with regular pins.

Pinterest has no intention of making money on the buy buttons. The company plans to monetize entirely with ads. Eventually, merchants will be able to amplify their shop-able items with ads from Pinterest.

The company provided some early results from small merchants. An online clothing boutique called Spool No. 72 reports that 84% of customers from buyable pins are new. A handmade goods shop called Madesmith reports that buyable pins represent around 7% of overall sales.

Earlier this summer, Pinterest announced it had reached 100 million monthly active users.

Watch Pinterest CEO Ben Silbermann speak at Fortune’s Brainstorm Tech conference: