Mozilla, which makes the Firefox web browser, officially released on Thursday its in-browser ad product, which the company first announced in February. Early adopters include media agency Mindshare North America, online booking site Booking.com, and The Weinstein Company’s video-on-demand portal Radius-TWC. How it works: Individuals opening Firefox for the first time will see tiles filled with ad content in their browser. For returning users, those tiles typically show images of frequently-visited sites. Users who’ve deleted their history will also see ad content. Firefox has a reputation as a browser that guards its users’ privacy at the expense of advertiser interests. While consumer advocates might see Firefox’s ad product as a reversal of that stance, Darren Herman, Mozilla’s VP of content, is quick to point out the user benefits. “The web is increasingly becoming more closed, and that move towards a closed ecosystem is not healthy for users,” he said. “The emergence of a closed Internet model among some of the biggest players is a huge threat to users of the Internet. And if it’s a threat to users of the Internet, it’s a threat to Mozilla.” Mozilla is also offering Enhanced Tiles, through which brand partners can personalize ad content. “It’s almost like cookie-less retargeting,” explained Herman. “Enhanced Tiles targets a user we know would go to your site, due to their browsing history, and offers advertisers the ability to put a piece of fresh content in front of that user from a site they’re used to seeing.” To support ad personalization, Mozilla created an internal data system that aggregates user information while stripping out personally identifiable information. Mozilla can track impressions, clicks, and the number of ads a user hides or pins. Its advertising partners are also privy to that data. Mindshare NA client CVS Health ran a trial the ad product, launching a campaign about how it removed tobacco from its retail outlets. Radius-TWC is testing the format for a branded campaign on the recently-released Edward Snowden documentary “Citizenfour.”

Users can turn off the ads, but they can also bookmark or pin ads they want to explore later.

So how does Mozilla sway advertisers, since Firefox users, more than users of any other browser, tend to block ads?

“If users are going to X out of ads, they were never going to respond to them anyway,” said Herman. “People who don’t want to see ads, or who have blocked advertisements entirely, aren’t going to perform too well for the advertiser anyway. We’ve basically put together an offering for people that are okay with seeing advertisements and wanting to interact.”

Though Mozilla is finally rolling out its ad product, Herman said there’s more work down the road. “What you see this week will continue to be optimized,” he said. “It’s not perfect, and we’re going up against some of the largest, closed or moving-toward-closed ecosystems out there, and we know we can’t do that alone.”

It possible, he said, that Mozilla might partner with ad tech vendors to enhance its offering. One potential partnership opportunity: programmatic. While those capabilities don’t exist in Mozilla’s ad product today, Herman said they inevitably will by the first half of 2015: “Due to the volume of scale that we have, there’s no way that we won’t be programmatic in the future.”