At DuckDuckGo, we do not collect or share any personal information. That's our privacy policy in a nutshell. For example, we do not store IP addresses, and we do not create unique cookies. As such, we do not even have the ability to create search histories or search sessions for any individual — privacy by design.

At the same time, we need a way to reliably improve our products for our users in an anonymous way. There are a few methods we've developed to achieve this.

First, you might notice that when you search DuckDuckGo, there may be an "&atb=" URL parameter in the web address at the top of your browser. This parameter allows us to anonymously A/B (split) test product changes we make to DuckDuckGo. For example, users in the A group would get blue links and users in the B group would get red links, and we'd be able to measure how usage of DuckDuckGo is impacted by different color links.

Second, we measure engagement of specific events on the page (e.g. when a misspelling message is displayed, and when it is clicked). This allows us to run experiments where we can test different misspelling messages and use CTR (click through rate) to determine the message's efficacy. If you are looking at network requests, these are the ones going to the one-pixel image at improving.duckduckgo.com. These requests are anonymous and the information is used only by us to improve our products.

Third, you may notice similar atb.js or exti requests made by our browser extensions and mobile apps. These requests help us anonymously count how many devices are using an experience. For example, our browser extensions and mobile apps will send an atb.js request with each search made. These requests allow us to count approximately how many devices accessed DuckDuckGo without knowing anything about those devices or the exact searches they made.

All of these requests are all fully encrypted in transit to DuckDuckGo, such that nobody else but us can see them. And like with all other requests to DuckDuckGo, there is no personally identifiable information embedded in them, and we do not store IP addresses associated with them.

To be clear, this means we cannot ever tell what individual people are doing since everyone is anonymous, and that is a limit of our statistical methods since we are private by design. We can, however, within this anonymous limitation, reliably determine what changes are generally working, using these anonymous methods.

We have developed these systems from scratch, instead of using third-party services, because of our privacy promise to never collect or share any personal information. We're proud to be able to improve our site for you in a completely anonymous way!

If you have any concerns, please feel free to reach out to us directly at privacy@duckduckgo.com.