Waterfall vs. header bidding

For years, publishers offered each impression to partners one at a time, in a fixed order.

By Brandon MinaCEO, BrandPilot AIUpdated November 2026

Lesson 4 of 9

SyllabusAll 9 lessons

Programmatic 101 · course overview

Learning objectives

By the end of this lesson, you can:

Describe how a waterfall works and why it left money on the table.
Explain how header bidding lets every buyer compete at once.
Compare client-side and server-side header bidding.

A tiered waterfall of coins beside many hands bidding at once around a table, 1960s ink-and-gouache magazine-ad illustration — The waterfall versus everyone at once

Waterfall calls partners one at a time; header bidding calls all SSPs at once

The lesson

A buyer further down the chain who would have paid more never got the chance. Header bidding changed that by asking many demand sources at the same moment and passing the best bid to the ad server. It's the single biggest structural shift in the sell side, and it explains why publishers work with so many SSPs today.

Header bidding changed that by asking many demand sources at the same moment and passing the best bid to the ad server.
Lesson 04 · Waterfall vs. header bidding

Compare waterfall and header bidding →

What's the Big Idea? Key takeaways

A waterfall offers impressions to one partner at a time and can miss higher bids.
Header bidding lets many buyers compete at once.
Server-side header bidding trades some transparency for speed.