Firefox just asked me to enroll in Firefox Pioneer. I'm definitely interested -- and the fact that I'm considering voluntarily sending browsing-derived data to Mozilla at all should speak highly to the trust that I have in y'all. I first started using Firefox over a decade ago, and while I've used other browsers since then I keep coming back to Firefox because 1) having an open source nonprofit web browser is critical to my values and 2) the customizability allows me to use Firefox in ways that simply aren't possible in other browsers. I'd like to be part of Pioneer in order to ensure you're aware of how I use Firefox to "make my vote count" I suppose, but as a very privacy and security-conscious individual, I really really dislike the idea of sending any more data than I have to. I understand you're anonymizing things but anonymized datasets have repeatedly been shown to be susceptible to de-anonymization. Despite my tin-foil hat, I'm still willing to be part of this on one condition: a clear answer that Pioneer does not send query string information. I understand losing query-string information would make a lot of pages look the same in the data because so many sites implement page indices in the query string rather than the path, but there's a lot of poorly-implemented websites that put tons of privacy-destroying information in query strings. You mention not sending POST data or cookies back as part of Pioneer, but you didn't mention query strings. I'm guessing they are, but in case they're not, let me know and I'll enroll in Pioneer.