Glossary
What is Bid adapter?
Also called: bidder adapter
A bid adapter is a plug-in that lets Prebid talk to one demand partner, turning its bid requests and responses into Prebid's format.
हिंदी में पढ़ेंEach SSP or exchange in Prebid has its own bid adapter. The adapter builds that partner’s bid request from your ad units and its bidder params, the IDs the partner needs to recognise your inventory, and turns its responses back into Prebid bids.
Your site does not load every adapter. Prebid lists more than 300 demand partners, but your build holds only the adapters and modules someone chose. If a bidder is added to the page setup but not to the build, Prebid cannot find it and logs an error that only shows in the browser console. No bids, no revenue line, no alert.
Adapters also change between versions. Prebid 11, released in March 2026, removed several adapters, and Prebid supports only its latest major version. After any partner change or upgrade, match your adapter list to every bidder contract and to each bidder’s line in ads.txt.
Example
A site signs a 6th SSP and adds it to the page setup, but the build still holds the old 5 adapters. The new partner sends 0 bids until the build is updated.
Why it matters to publishers
A missing or outdated adapter silently removes a bidder from your auction, so checking the build is a quick win after any partner change.