This document describes the mechancis of a Prebid Server cookie sync.
Many Bidders track users through Cookies. Since Bidders will generally serve ads from a different domain than where Prebid Server is hosted, those cookies must be consolidated under the Prebid Server domain so that they can be sent to each demand source in /openrtb2/auction calls.
Start by calling
/cookie_sync. For each element of
GET element.usersync.url. That endpoint should respond with a redirect which will complete the cookie sync.
Bidders who support cookie syncs must implement an endpoint under their domain which accepts an encoded URI for redirects. For example:
This example endpoint would URL-decode the
redirectUri param to get
It would then replace the
$UID macro with the user’s ID from their cookie. Supposing this user’s ID was “132”,
it would then return a redirect to
Prebid Server would then save this ID mapping of
somebidder: 132 under the cookie at
When the client then calls
www.prebid-domain.com/openrtb2/auction, the ID for
somebidder will be available in the Cookie.
Prebid Server will then stick this into
request.user.buyeruid in the OpenRTB request it sends to