Bidder adapter

A bidder adapter is the module inside Prebid.js or Prebid Server that converts a header bidding auction into one demand partner's request format and turns that partner's response back into standard bids.

In Prebid.js, every adapter implements the same small set of functions. The isBidRequestValid function checks the publisher's settings for that bidder. The buildRequests function builds the calls to the bidder's server. The interpretResponse function parses the reply into bid objects. The getUserSyncs function registers sync pixels when the publisher allows them (Prebid.org, accessed 9 November 2026).

Each bid an adapter returns must carry certain fields. They include a price, a creative ID, a ttl that says how many seconds the bid stays usable, and netRevenue, which says whether the price is net or gross. Adapters may not fire network calls of their own beyond the requests and syncs the wrapper makes for them. Prebid's rule is that each demand company maintains its own adapter, so fixes come from the party that knows the endpoint.

Prebid Server uses the same idea on the server side, with adapters written in Go or Java that send OpenRTB to each bidder.

Example: On 9 November 2026 the Prebid Server (Go) repository held 280 adapter folders and 397 bidder configuration files, which include aliases, by our count (GitHub, prebid/prebid-server adapters). A new SSP joining Prebid adds one folder, one configuration file and tests, then waits for review.

Related terms: Prebid.js, Prebid Server, header bidding wrapper, bid response, cookie sync, OpenRTB.

Authoritative source: Prebid.org, "How to Add a New Prebid.js Bidder Adapter" (accessed 9 November 2026).

Read the full guide: Prebid Server bidder adapters: the list and how to add one.