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User Synchronization in OpenRTB S2S Integrations


Last updated on September 19, 2017

The ad tech industry has several names for user synchronization. You may know it as “user mapping”, “user matching”, “cookie mapping”, “cookie syncing”, or “cookie matching”. The calls and steps of the user synchronization process itself are also described differently throughout the industry.

Synchronizing users with OpenX enables all parties in the advertising value chain to identify a particular user.

The majority of advertisers run performance-based advertising campaigns. As such, most demand-side platforms (DSPs) do not bid, or bid low in advertising exchanges (including OpenX) when a user ID is not present. Therefore, synchronizing your users provides a clear advantage for drawing in additional advertiser spend.

For desktop and mobile web, user synchronization is required for effective monetization and must precede turning on live requests. User synchronization does not apply to mobile app traffic.


Make sure you meet the following requirements:

  • Initiate the synchronization.
  • Ensure bid requests contain user IDs.
  • Create, host, and manage the cookie-matching table, which maps your cookies to OpenX’s.
  • Append OpenX cookie ID in your requests to OpenX.

How User Synchronization Works

Receiving a user ID and storing it to your User ID match table follows this process:

  1. You send OpenX your User ID for a viewer.

  2. OpenX sends you the OpenX User ID for that viewer.

  3. You store the IDs in your User ID match table.