Skip to main content

Header Bidding 101

Understand how header bidding works and why it tends to earn more than traditional ad serving.

What is header bidding?​

Header bidding is a technique where multiple demand sources bid on your ad inventory simultaneously, before your ad server (like Google Ad Manager) is called. Because every source competes at once, your inventory tends to clear at a higher price than when partners are asked one at a time.

Waterfall vs. header bidding​

Before header bidding, publishers used a waterfall: demand partners were called one at a time, in a fixed order based on past performance. A partner lower in the order might have paid more, but was never asked once someone above it filled the slot.

Header bidding replaces that with a simultaneous auction — every partner bids at once, so price wins on merit rather than queue position:

The highest eligible header-bidding bid is passed to GAM, but GAM makes the final serving decision: a direct deal or a higher-priority line item can still win over a larger open-market bid.

Why it matters for you​

MetricWaterfallHeader bidding
Average CPM$1.50$2.10
Fill rate70%85%
RevenueBaseline+30–50%

Numbers are illustrative. Actual results vary by site, geography, and vertical.

How Anima implements header bidding​

Key concepts​

The vocabulary here — demand partners, Auction Timeout, floor price, Prebid.js — is defined in the Glossary. The one-line version: Anima runs Prebid.js under the hood and manages its configuration for you, so you work in terms of slots, partners, and floors rather than raw Prebid code.

Common questions​

Does header bidding slow down my site?

It adds some latency (typically 500-1500ms for the auction). However:

  • Modern implementations are highly optimized
  • Lazy loading means only visible slots delay page render
  • Revenue gains typically far outweigh minor speed impact
  • You can tune timeout settings to balance speed vs. revenue

Learn more: Revenue vs. Latency →

How many demand partners should I have?

5-10 partners is typical for most publishers.

  • Too few (< 3): Not enough competition
  • Sweet spot (5-10): Good competition, manageable complexity
  • Too many (> 15): Diminishing returns, slower auctions

Quality matters more than quantity. Focus on partners strong in your geography and vertical.

Does header bidding work with Google Ad Manager?

Yes, and it's designed to. The header bidding auction runs first, then the winning bid competes with your direct deals and AdSense/AdX in GAM. GAM still makes the final decision on what serves.

Is header bidding only for big publishers?

No. While enterprise publishers pioneered it, header bidding benefits publishers of all sizes. If you're running programmatic ads, header bidding likely increases your revenue.