Open Bidding vs Header Bidding: Which Suits a Smaller Site?

Once you move from AdSense into Google Ad Manager, you will hear two terms that sound alike: Open Bidding and header bidding. Both bring more buyers into the auction for each ad slot. They do it in different places, with different amounts of work and different requirements. This guide compares them head to head for a smaller site that is new to Ad Manager, and suggests a sensible order for trying them.

The problem both solve (more demand per impression)

With AdSense, Google decides which ad fills each slot. In Ad Manager, your ad server can consider several sources at once: Ad Exchange (AdX) buyers, any line items you set up, and third-party exchanges or networks. The more qualified buyers that compete for an impression, the better the chance that the highest value bid wins.

The challenge is getting those outside buyers into the same decision as Google's demand, in real time, without slowing the page. Ad Manager handles the competition through dynamic allocation, which our guide to dynamic allocation explains in more detail. Open Bidding and header bidding are two routes for getting third-party bids into that competition.

Open Bidding: server-to-server inside Ad Manager

Open Bidding is Google's server-side option. Google describes it as a "server-to-server" integration between publishers and their demand partners. Here is the sequence, simplified from Google's help center:

1. The page sends an ad request to Ad Manager through Google Publisher Tag (GPT), as usual.
2. Ad Manager picks the best eligible line item and, at the same time, sends bid requests to the third-party yield partners listed in your yield groups.
3. Each yield partner runs its own auction and returns its best bid.
4. Ad Manager runs a unified auction where yield partner bids, the Ad Exchange bid and your line items compete. Every participant competes on a net basis, and each bids once per impression.
5. The winning ad is returned to the page.

A few details are worth knowing:

• No extra code on the page. Open Bidding uses your existing tagging, so there is no bidding script running in the visitor's browser.
• Availability. Google's Open Bidding FAQ says it was originally limited to Ad Manager 360 but is now available for all publishers using Ad Exchange in Ad Manager. Standard Ad Manager publishers onboard online after agreeing to the Open Bidding terms.
• Partners must accept you. A yield partner may need to pretarget your network code before it sends bids. If it has not, Ad Manager shows an error saying the exchange is not accepting requests from your network.
• Some controls work differently. Competitive exclusions set in Ad Manager do not apply to Open Bidding demand and must be set up with the exchanges. Requests marked as child-directed under COPPA are not sent to Open Bidding partners.

Header bidding: bids collected in the page first

Header bidding works the other way around. In Google's words, it is a system that collects programmatic bids on the publisher's webpage before making the ad request to Ad Manager. A script on your page (usually called a wrapper) asks several exchanges for bids, waits a short time, and then passes the results to Ad Manager along with the ad request. Ad Manager then compares those bids with its own demand.

The most common wrapper is Prebid, which describes itself as free and fully open source. Prebid.js runs the auction in the browser before the ad server call and uses a single timeout to limit how long the page waits for bids.

How the bids enter Ad Manager depends on your account:

• The traditional approach maps header bids to Price Priority line items that you create in Ad Manager at set price points. This works in any Ad Manager account but means building and maintaining those line items.
• Header bidding trafficking, a newer Ad Manager feature, lets bids compete with their true values instead of through Price Priority line items, with simpler setup and consolidated reporting. Google lists it as available only in Ad Manager 360, and it requires the Prebid wrapper with a standard implementation, GPT on the site, the banner format and web inventory. It is found under Delivery > Bidders in a 360 network.

Header bidding also asks more of you outside Ad Manager. You typically need a direct relationship with each bidder in your wrapper, and someone has to maintain the wrapper code as bidders and browsers change.

Side by side: setup, latency, transparency, control

Neither column is "better" in every case. Open Bidding is simpler and lighter on the page. Header bidding gives more hands-on control and access to bidders that may not be available as Open Bidding partners, at the cost of more engineering time.

Which features need Ad Manager 360

This is where many guides get it wrong, so here is the short version based on Google's help pages:

• Open Bidding: available to all publishers using Ad Exchange in Ad Manager, not only 360.
• Header bidding with your own wrapper and Price Priority line items: possible in any Ad Manager account.
• Header bidding trafficking (the built-in Prebid integration): Ad Manager 360 only. Google lists it among the 360 features alongside items such as Data Transfer reporting and Teams.

If you are weighing the two account types more broadly, our guide on Ad Manager vs Ad Manager 360 covers the differences and the impression thresholds that apply to the standard account.

How floors (UPR) apply to both

Unified pricing rules (UPR) are Ad Manager's central place to set floor prices for non-guaranteed demand. Google's help page lists what they cover, and both routes are on the list:

• third-party exchanges that take part in Open Bidding;
• remnant line items, including the Price Priority line items used in traditional header bidding setups;
• header bidding trafficking demand in Ad Manager 360.

A few rules matter in practice. If two pricing rules target overlapping inventory, the higher price applies. A network can have up to 200 unified pricing rules. Pricing rules do not apply to Programmatic Direct deals, which our guide to programmatic deals covers.

Floors in the header bidding wrapper itself are a separate setting. If you run both, keep the two in step so one does not quietly undercut the other.

A sensible order for a site new to Ad Manager

For a smaller publisher moving up from AdSense, there is no prize for running the most complex stack on day one. A calm sequence looks like this:

1. Get the basics stable. Sites approved, ads.txt correct, GPT tags working, Ad Exchange serving, and reports you understand. Note a baseline for revenue, page speed and viewability.
2. Set floors carefully. Start with modest unified pricing rules and adjust based on what you see, rather than copying numbers from forums.
3. Try Open Bidding next, if it is available to you. It adds third-party competition without new page code, which makes it a natural first step. Add a small number of yield partners and watch the results.
4. Consider header bidding later. If you have someone who can maintain a wrapper and you have specific bidders in mind, test it on part of your traffic. Compare page speed and revenue against your baseline before rolling it out.

If you join through an MCM partner

Under Multiple Customer Management (MCM), your partner usually handles much of this setup. Google's Open Bidding FAQ states that Open Bidding is compatible with MCM and can be used with MCM child publishers. Whether it is actually active for your inventory, and which bidders are included, depends on your account and your MCM partner's setup.

Two details from Google's Manage Account documentation are useful to know. Payment facilitation in Manage Account covers Open Bidding earnings, except where the third-party demand partner pays the child (or someone on the child's behalf) directly. And while a bidder shows the status "Onboard online started" in the child account, the Manage Account parent cannot adjust that bidder's settings. Header bidding is a separate decision, since it involves code on your pages, so agree with your partner who maintains it before adding a wrapper. The guide on how MCM works explains the two delegation types.

Next step

Both Open Bidding and header bidding sit on top of a working Ad Manager and Ad Exchange setup, so the first step is getting that foundation in place. Through an MCM partner, eligible publishers may receive an invitation to monetize with AdX, subject to Google's policies, and can then decide with the partner which extra demand makes sense.

Get AdX access or check the requirements first.