All marketers will soon be able to use information shoppers share with them off of Facebook to target ads on the social network.

Facebook announced today it has begun broadening access to its Custom Audience tool. It lets advertisers target customers based on information shoppers have shared with the marketer off of Facebook, such as their e-mail addresses, phone numbers and, for game and application developers, their user names.

Previously only advertisers who use the social network’s application programming interface or Power Editor ad-management tool had access to Custom Audience. Power Editor aims to streamline the process of creating and managing multiple advertising ad campaigns on the social network by allowing marketers to change settings, targeting, bids, budgets and creative elements across ads, campaigns and even accounts.

The move will give many smaller retailers and other advertisers access to a tool that many merchants have found effective. For instance, in the first two months that shopping-focused social network OpenSky.com used the tool, its targeted ads had a 30% higher conversion rate—a consumer clicked on the ad and made a purchase—than its other Facebook ads. Moreover, 70% of the shoppers who made purchases had signed up to receive OpenSky’s e-mails but never made a purchase.

Here’s how Custom Audience tool works: the retailer uploads its customer information, such as an e-mail list, using Facebook’s ad management tool. The retailer scrambles that information, creating what cryptographers call a “hash” that can’t be decoded to recreate the individual addresses. Facebook does the same with its users’ information. Facebook then matches up the retailer’s hashes with its hashed user accounts. The retailer can target that matched group with any of the social network’s ad formats. It can also focus on particular segments, like men in Seattle who are between 30 and 40 years old.

The social network says that today it began expanding access to Custom Audience to a limited number of U.S. advertisers, with a global rollout starting next week. All advertisers will have access to the tool by late November, says a spokeswoman.

Facebook also added functionality that lets marketers upload their e-mail subscriber lists from e-mail services provider MailChimp to target consumers. 48 of the 1,000 largest online retailers in North America use MailChimp to handle their e-mail marketing, according to Internet Retailer’s Top500Guide.com.

Facebook last week began letting marketers use Custom Audience to retarget consumers who visit their web sites or mobile apps but leave before completing a purchase. Previously the social network limited retargeting to its ad-bidding network, Facebook Exchange, which requires marketers to work with vendors to bid on ads.

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