We do use cookies for part of the analysis, but they're not unique user-tracking cookies. Instead there's one that simply tracks a self-reported datestamp on when the user last visited, which looks something like:
WMF-Last-Access=2023-01-01,Expires=Wed, 01 Feb 2023 12:00:00 GMT
(we send a Set-Cookie for this with the current datestamp only to the 1-day accuracy, which expires ~32 days after it's set (but rounded to 12-hour accuracy), and is replaced constantly).
There's another more-recent one we use that's explicitly about differential privacy, which send back info on the hashes of the 10 most recent URLs you've visited on the site, IIRC. None of them are unique tracker hashes for a given user, though.
>which send back info on the hashes of the 10 most recent URLs you've visited on the site, IIRC. None of them are unique tracker hashes for a given user, though.
That seems highly unlikely to never be unique for some users.
The hash is keyed and rotates once a day, so it's not a long-term history. And in any case, nobody's trying to build a unique tracker out of it on the other end, which is the main thing (even in our internal analytics, we even throw away the PII we get directly from request attributes after 90 days).
We do use cookies for part of the analysis, but they're not unique user-tracking cookies. Instead there's one that simply tracks a self-reported datestamp on when the user last visited, which looks something like:
WMF-Last-Access=2023-01-01,Expires=Wed, 01 Feb 2023 12:00:00 GMT
(we send a Set-Cookie for this with the current datestamp only to the 1-day accuracy, which expires ~32 days after it's set (but rounded to 12-hour accuracy), and is replaced constantly).
There's another more-recent one we use that's explicitly about differential privacy, which send back info on the hashes of the 10 most recent URLs you've visited on the site, IIRC. None of them are unique tracker hashes for a given user, though.