Site Improvements (&atb=, /t/)

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 site for our users in an anonymous way, and there are a few ways we’ve developed to do so. 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 is a private method we developed to help us anonymously A/B (split) test experience changes we make to DuckDuckGo. For example, we may show one misspelling message to the A version and another to the B version, and then check statistically which message version gets more engagement.

Second, 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 only send one type of these requests a day, which means we can count approximately how many devices accessed DuckDuckGo without knowing anything about those devices or the searches they made.

Third, we also measure engagement for various experiments by sending anonymous requests when specific events happen (e.g. when a misspelling message is clicked). If you are looking at network requests, these are the ones going to the one-pixel image at

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