Header bidding replaced legacy waterfall mediation by allowing all demand sources to bid simultaneously on impressions, boosting effective publisher CPMs by 35%+.
1. Client-Side Prebid vs. Server-to-Server (S2S)
- Client-Side Prebid.js: Maximizes cookie matching and device identity resolution, but introduces multiple parallel browser HTTP connections.
- Prebid Server (S2S): Replaces 10+ client calls with a single JSON payload to an edge proxy, reducing Core Web Vitals LCP latency by 350ms.
- Hybrid Orchestration: Client-side bidding for top 3 high-value SSPs with server-side fanout for secondary programmatic demand.