Not one to get left behind, Facebook on Wednesday announced that it will let more merchants sell products directly over its service by launching a buy button beta program with Shopify. The news comes weeks after similar announcements by Google and Pinterest, which are also stepping up their efforts in e-commerce.

Facebook's buy button lets merchants sell products directly over the social network, making it easy for users to shop without having to leave the service. Facebook has been testing this with a select few merchants since last July, but now, the social network will be opening up the feature to many more businesses.

Shopify said it has begun inviting U.S.-based merchants into the program, allowing them to post products with buy buttons, which they can then promote by paying for Facebook advertisements. Shopify said it will not be making the feature available to all sellers, but those interested in receiving an invitation can sign up on Shopify's website to "express your interest in joining the beta test."

For Facebook, the Shopify beta test is all about keeping up with the Joneses. Just last week, Pinterest said it will introduce Buyable Pins later this month, a feature that will let retailers sell products over the social network, while Google two weeks ago confirmed its plans to introduce a buy button for search results, although it has yet to reveal the details of its feature. Twitter also has been testing a buy button, recently letting sports teams and artists use the feature to sell tickets to their events. 

Retailers are hoping the rise of buy buttons across social networks and Google will make it easier for users to shop on smartphones and give a boost to their e-commerce sales. For the tech companies, adding a buy button is another way to get retailers to pay for advertisements. Rather than taking a cut from each transaction, the companies let retailers add buy buttons for free, then pay to promote their products.