How to Add a New Bidder Adaptor

At a high level, a bidder adapter is responsible for:

  1. Sending out bid requests to the ad server
  2. Registering the bids that are returned with Prebid.js

This page has instructions for writing your own bidder adapter. The instructions here try to walk you through some of the code you’ll need to write for your adapter. When in doubt, use the working adapters in the Github repo for reference.

Step 1: Prepare prerequisites for a pull request

In your PR to add the new adapter, please provide the following information:

  • The contact email of the adapter’s maintainer.
  • A test ad unit that will consistently return test creatives. This helps us to ensure future Prebid.js updates do not break your adapter.

Step 2: Add a new bidder JS file

  1. Create a JS file under src/adapters with the name of the bidder, e.g., rubicon.js

  2. Create an adapter factory function with the signature shown below:

var bidfactory = require('../bidfactory.js');
var bidmanager = require('../bidmanager.js');

var BidderNameAdapter = function BidderNameAdapter() {

    function _callBids(params){}

    // Export the `callBids` function, so that Prebid.js can execute
    // this function when the page asks to send out bid requests.
    return {
        callBids: _callBids

module.exports = BidderNameAdapter;

A good example of an adapter that uses this pattern for its implementation is OpenX.

Step 3: Design your bid params

Use the bid.params object for defining the parameters of your ad request. At a minimum, you should include the tag ID and the site ID. You can also include ad sizes, keywords, and other data, such as video bidding information.

For more information about the kinds of information that can be passed using these parameters, see the list of bidder parameters.

For example, if your bidder supports serving video ads, you could add a video object to your adapter’s bid parameters like the AppNexus AST adapter. To see how those video params are processed and added to the ad tag, see the AST adapter’s implementation of the callBids function.

For more information about how the implementation of callBids should work generally, see the next section.

Step 4: Send out bid requests

When the page asks Prebid.js to send out bid requests, your bidder’s _callBids(params) function will be executed. This is a good place for you to send out bid requests to your bidder.


function _callBids(params) {
    bids = params.bids || [];
    for (var i = 0; i < bids.length; i++) {
        var bid = bids[i];
        // Send out bid request for each bid given its tag IDs and query strings
    // Or, send out 1 bid request for all bids, depending on your bidder.

The params object contains information about the bids configured in the request:

    bidderCode: "openx",
    bids: [
            bidder: "openx",
            adUnitCode: "id123/header-bid-tag-0",
            sizes: [ [300, 250], [300, 600] ]
            // params is custom to the bidder adapter and will be
            // passed through from the configuration as is.
            params: { 
            	unit: '3242432',
                pgid: '123124',
                jstag_url: 'http://...'
        }, {
        	bidder: "openx",
        	// params, adUnit Code, and sizes
        	// Note that the same adUnitCode may appear again.

Note that you should keep track of the adUnitCode in bid requests. In the next section this will come in handy.

Step 5: Register bid responses

When the bid response(s) are available, notify Prebid.js immediately, so that your bid can get into the auction as soon as possible. A bidder’s API will usually have an event listener that notifies you when the bid responses are back.

To register the bid, call the bidmanager.addBidResponse(adUnitCode, bidObject) function. To register multiple bids, call the function multiple times.

  • If the bid is valid, use bidfactory.createBid(1) to create the bidObject. A status of 1 means the bid is valid. For details about the status codes, see constants.json.
  • If the bid is invalid (no fill or error), use bidfactory.createBid(2) to create the bidObject. A status of 2 means “no bid”.

If your bidder supports serving video ads, it needs to provide a VAST video URL in its response. On the adapter side, your implementation of createBid needs to add the VAST URL to the bid. For an example implementation, see the implementation in the AST adapter.


// In the bidder's API callback...

// the bidder API's ad response unit that has info like CPM, creative content
var adUnit;

var bidObject = bidfactory.createBid(1);
bidObject.bidderCode = 'openx';
bidObject.cpm = Number(adUnit.get('pub_rev')) / 1000; = adUnit.get('html');
bidObject.width = adUnit.get('width');
bidObject.height = adUnit.get('height');

// send the bidResponse object to bid manager with the adUnitCode.
bidmanager.addBidResponse(adUnitCode, bidObject);

// invalid bid response
bidObject = bidfactory.createBid(2);
bidObject.bidderCode = 'openx';
bidmanager.addBidResponse(adUnitCode, bidObject);

adUnitCode in addBidResponse

In bidder API’s callback, there’ll be ID(s) that tie back to the request params in the bid object. Building a map from adUnitCode to the request param(s)/ID(s) will help you retrieve the adUnitCode based on the callback.

bidObject in addBidResponse

The required parameters to add into bidObject are:

Key Scope Description Example
bidderCode Required The bidder code. "pubmatic"
cpm Required The bid price. We recommend the most granular price a bidder can provide 3.5764
width Required The width of the returned creative. 300
height Required The height of the returned creative. 250
ad Required The creative payload of the returned bid "<html><h3>I am an ad</h3></html>"

Helper functions

adloader.loadScript(scriptURL, callback, cacheRequest)

Load a script asynchronously. The callback function will be executed when the script finishes loading.

Use this with the cacheRequest argument set to true if the script you’re loading is a library or something else that doesn’t change between requests. It will cache the script so you don’t have to wait for it to load before firing the supplied callback.

For usage examples, see the working adapters in the repo.

Further Reading