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Open Private Join and Activation (OPJA)

Last updated: February 14, 2024

About OPJA

Open Private Join and Activation (OPJA) is a specification that will enable an advertiser to reach an audience of users with which they have an existing relationship (for example, a list of the advertiser’s customers or of users subscribed to the advertiser’s loyalty program) without the need for tracking users more broadly across the internet to find their customers. The specification defines a two-party operation and supporting mechanisms which together enable secure and privacy-protecting activation of advertiser’s existing customers on a publisher website or mobile app or a Connected Television (CTV) streaming app etc. OPJA enables an advertiser to activate the subset of the publisher’s users that are also present in the advertiser’s list by performing a secure match with user match keys (such as email addresses). This enables a participant to to target the resulting overlap, all without revealing who the matched users are. We chose to initially focus on OPJA both because of its benefits to end-user privacy, as well as to publishers and advertisers working with identified first party data.


This is a first in the series of Data Clean Room interoperability  standards  that describes the specification for activating matching audiences between two parties. It describes the process and privacy enhancing technologies (PETs) deployment for  implementing a matching operation between two parties and the supporting mechanisms to use the output of the operation to activate matched audience for advertising.