What is Prebid?
Prebid is a family of free, open-source header bidding tools, including Prebid.js for websites, Prebid Server and Prebid Mobile, maintained by the independent industry group Prebid.org. It lets publishers run auctions among many ad exchanges and SSPs at once, then pass the winning bid to their ad server, without depending on one vendor's proprietary wrapper.
Prebid began at AppNexus in 2015 and moved to Prebid.org, founded in 2017, whose members include SSPs, publishers and other ad tech firms. Each demand partner writes an "adapter"; publishers pick the adapters they want, configure floor prices and auction timeouts, and add modules for identity, consent and supplyChain object passing.
Prebid's reach grew further in 2026: Judge Brinkema's remedies decision in the US ad tech case ordered Google to build integrations connecting its ad exchange and publisher ad server with Prebid, subject to a final judgment and appeals. Server-side header bidding via Prebid Server is common in apps and CTV.