If you're a publisher trying to maximize your ad revenue, you've likely come across two terms: header bidding and waterfall. These are the two primary methods for selling your ad inventory to advertisers — and the difference between them can mean thousands of dollars in monthly revenue.
What is the Waterfall Method?
The waterfall method (also called daisy chaining) is the traditional approach to programmatic ad selling. In this model, your ad server calls demand sources one at a time, in a pre-set priority order — like water flowing down a waterfall.
Here's how it works:
- Your ad server first calls the highest-priority demand source (usually Google AdSense or your direct deals).
- If that source doesn't fill the impression at your floor price, it passes to the next source.
- This continues down the chain until an ad is served or the impression goes unfilled.
💡 The problem with waterfall: Lower-priority networks never get a fair chance to bid, even if they would have paid more. This leaves significant revenue on the table.
What is Header Bidding?
Header bidding (also called pre-bidding or advanced bidding) is a more modern, sophisticated approach. Instead of calling demand sources one at a time, header bidding allows multiple SSPs and ad exchanges to bid simultaneously for your inventory — before your ad server makes its final decision.
The name comes from the fact that the auction code runs in the <head> section of your webpage, before the page fully loads.
Header Bidding vs Waterfall: Side-by-Side Comparison
| Feature | Waterfall | Header Bidding |
|---|---|---|
| Bidding method | Sequential (one at a time) | Simultaneous (all at once) |
| Competition | Limited — lower networks rarely bid | Maximum — all SSPs compete equally |
| Revenue potential | Lower | Up to 30-50% higher |
| Latency | Can be slow (sequential calls) | Faster (parallel calls) |
| Complexity | Simple to set up | Requires technical setup |
| Transparency | Low | High |
How Does Header Bidding Increase Revenue?
The key advantage of header bidding is increased competition. When 10-15 SSPs all bid simultaneously for the same impression, the highest bidder wins — regardless of their position in any priority list.
This means:
- Every impression gets its true market value
- Premium demand sources that were previously blocked by waterfall priority can now compete
- Publishers see higher eCPMs across all ad units
- Fill rates improve because more buyers are competing
Types of Header Bidding
1. Client-Side Header Bidding
The most common form. JavaScript code runs in the user's browser, sending bid requests to multiple SSPs simultaneously. Uses Prebid.js as the industry-standard wrapper.
2. Server-Side Header Bidding
Bid requests are sent from a server rather than the user's browser. This reduces page latency but can result in slightly lower bid accuracy due to cookie matching challenges.
3. Hybrid Header Bidding
A combination of both approaches — some SSPs are called client-side, others server-side. This balances performance and revenue optimization.
Should You Switch from Waterfall to Header Bidding?
For most publishers with significant traffic (100K+ daily visitors), the answer is yes. The revenue uplift from header bidding typically far outweighs the implementation complexity — especially when you work with a managed partner like Pubixa.
Pubixa's Header Suite connects you to 10-15 premium SSPs simultaneously, with full managed setup and ongoing optimization. Publishers typically see a 20-40% revenue increase within the first 90 days.