Prebid Server Documentation

Prebid Server works extremely closely with Prebid.js. For information on getting started with prebid.js, check out the getting started with prebid.js page on

What is this?

Prebid Server is a server-to-server header bidding solution for prebid.js, released and hosted by AppNexus. It's free to use for publishers who have audited domains on AppNexus, and allows those publishers to configure select header bidding demand partners to work through a server-side connection, rather than being called directly from the browser. This can have performance benefits, which helps you make sure that you can have an excellent user experience while also taking advantage of the monetization gains from header bidding.

Getting Started

Step 1: Get a Prebid Server Account

Pretty simple! Register and create an account here. Copy down your prebid server ID.

Step 2: Download Prebid.js with Prebid Server enabled

Navigate to and select all the demand adapters you wish to work with, and be sure to include the "Prebid Server" adapter.

For example, if you wanted to support AppNexus and FAN server-side, and Index Exchange client-side, you would select "AppNexus", "FAN", "Index Exchange," and "Prebid Server."

Click the "get custom prebid.js" link and follow the instructions to receive the build.

Step 3: Incorporate the build and configure S2S Bidder Adapters

On your site, make sure you now link to the new version of prebid.js that you built in Step 2.

Add a new section to your prebid.js config:

      accountId : '1',                            //string:required: account ID obtained in step 1
      enabled : true,                             //boolean:required: enables s2s - default false
      bidders : ['appnexus','audienceNetwork'],   //array[string]:required: of bidder codes to enable S2S.
                                                  //Note these must have been including in the Prebid.js build from Step 2.
      timeout : 1000,                             //number:optional timeout in ms for bidders called via the S2S endpoint.
                                                  //default value is 1000
      adapter : 'prebidServer'                    //string:optional: Adapter code for S2S code. Defaults to 'prebidServer'
      cookieSet : true                            //boolean:optional: If 'false' (not recommended), opt out of link rewriting
                                                  //and cookie-setting that allow a persistent cookie for improved cookie
                                                  //match rates.
                                                  //Defaults to 'true'.

Additional cookieSet details

We recommend that users leave cookieSet enabled since it's essential for server-to-server header bidding that we have a persistent cookie for improved cookie match rates. If set to false:


What demand partners work with Prebid Server?

We're announcing our full partner set soon -- stay tuned.

How does cookie syncing work with Prebid Server?

Prebid Server doesn't require partners to cookie sync with it in a traditional RTB fashion. When we determine that we need a partner's user ID for an end user, we'll grab that partner's ID for that user and store it in a client-side cookie. On subsequent calls, we'll use that partner's ID directly, rather than requiring partners to sync with one another.

How much does Prebid Server cost?

Prebid Server is free to publishers, and there are no charges to demand partners who are integrated.

If it's free, why is AppNexus doing this?

AppNexus believes that it's important for header bidding to remain a fair and transparent technique, and it's clear that server-to-server is an important evolution for header bidding. We want to make sure that everyone can take advantage of server-to-server without relying on any black box technology.

Does AppNexus have any advantages in Prebid Server?

No demand partner, including AppNexus, has any advantage over another in Prebid Server. It's designed to be a separate transparent and fair system, and doesn't give any bias to any partner.

Do I have to be an AppNexus customer to use Prebid Server?

Prebid Server is available to all quality publishers, regardless of if they participate in the AppNexus exchange or not.

How do companies get involved with being S2S partners connected into Prebid Server?

Get in touch at

What's the "auction model" of Prebid Server? What bids will it return or not return?

Prebid Server is a transparent passthrough, so it doesn't do any auctioning by itself. It returns all bids from demand partners to the page, and prebid.js passes them to the ad server -- all just like normal header bidding, only with the benefits of server-to-server connections.

Are Deal ID bids supported in Prebid Server? How do those work?

You can set up deals as normal in your preferred SSPs of choice. When those demand partners return a deal ID, we'll return that to prebid.js. Learn more about deals in prebid.js here:

Is there any bid landscape or log of the server-side bids?

All bids are returned to prebid.js, so you can see what's going on within prebid.

I have a question about Prebid Server, who can answer it?

Prebid Server is a prebid project. Check out to learn more.