# Duck Tales: How DuckDuckGo blocks trackers on third-party websites (Ep.17)

An episode of [Inside DuckDuckGo](https://invisiblenetwork.ai/podcast/1839957193), 4 Feb 2026, 15 min.

Audio: https://api.substack.com/feed/podcast/186627241/bad1d5ff307f3ac30c159b0b6e32c5c7.mp3

This episode, Beah (Chief Product Officer) and Dave (Privacy team) discuss our tracker blocklist, how it works, and why most of it is open source. Disclaimers: (1) The audio, video (above), and transcript (below) have been lightly edited for clarity. However, they may still contain some minor inaccuracies or transcription errors. (2) This website is operated by Substack. This is their privacy policy. Beah: Hello and welcome to DuckTales where we go behind the scenes at DuckDuckGo and discuss stories, technology and people that help build privacy tools for everyone. In each episode we talk about like something going on with our product or our company or our company vision and or how we operate and today we have our guest is Dave, who’s here to talk about the tracker block list. Hi, Dave. Dave: Hey, Beah. Thanks for having me on. Yeah, sure thing. Yeah, my name is Dave Harbage. I’m a privacy engineer at DuckDuckGo. I primarily work on identifying privacy threats, building features to protect our users from these threats, and ensuring that we deliver a great web browsing experience. Beah: Do you wanna introduce yourself briefly? That sounds very important, Dave. Dave: Yeah, yeah, it’s a constant battle. It’s trying to keep up with the developing environment and give our users a good experience. Beah: Thanks for fighting a good fight. So if I’ve hosted, if you’ve seen other DuckTales, you might have met me, but if you haven’t, I’m Beah and I am on the product team here. So yeah, let’s talk a bit about the tracker block list. First of all, what even is it? Dave: Yeah, so our tracker block list is a list of domains and URLs that we found to exhibit what we call cross-site tracking behaviors. We use it in our browsers and browser extensions to block tracking requests and enhance the privacy of our users. Beah: Sweet. So what’s the point of all that? Why did we even make this thing? Dave: Yeah, so at DuckDuckGo, we believe that privacy is a fundamental human right. And we believe that people should have the option to live their lives without third parties recording their every move. We realized that protecting users’ privacy on our search engine was only half of the battle. As soon as users leave our search engine page to visit other websites, they’re subject to these third parties tracking their activities anywhere they go on the web. Pretty much. I think you might be shocked at just how many companies are involved in tracking your activity and also the granularity of the data that they’re collecting. For example, we’ve seen individual websites load hundreds of different tracking requests on a single page load. And it’s all hidden to the users. So we decided that we wanted to build a product that protects our users’ privacy not just when they’re searching, but when they’re browsing the web. Beah: Yeah, do you know like approximately what portion of websites or maybe of web traffic is to a site with or to a page that has trackers on it? Dave: I don’t have the exact number on the top of my head. It is... Beah: I feel like the last I looked at the data, which was a little while ago, was like something on the order of 90%. Dave: Yeah, it’s up there. It’s apps that you install on your phone. It’s websites that you visit in a browser. It’s incredibly prevalent everywhere. Beah: Yeah, so basic premise here, like I mean I’m sure there’s a lot of people listening who like know this in their sleep, but then for those who don’t, it’s like as you move around the web, there may be these hidden trackers that have no explicit connection to the site itself. Google specifically is on just a ton of pages on the internet. So you’re on some random website, like a community, maybe the school your child goes to or something like that. And Google is actually there watching what you do in some sense, collecting data on your behaviors. Dave: Yeah, that’s exactly right. There are many different reasons that websites add these third parties to…

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