Glossary/Adtech & Programmatic/Server-to-Server (S2S) Header Bidding
Adtech & Programmatic
Server-to-Server (S2S) Header Bidding
Header bidding where the auction runs on a server, such as Prebid Server, instead of in the user's browser, reducing page latency.
By Brandon Mina·CEO, BrandPilot AI·Updated November 2026
Appears in Lesson 4 of Programmatic 101
Short answer
Server-to-server (S2S) header bidding is a form of header bidding in which the auction runs on a server, such as Prebid Server, rather than in the user's browser. Moving bid requests off the page reduces latency and allows more demand partners. The trade-off can be weaker user matching and less transparency than client-side auctions.