Prebid Server

Prebid Server (PBS) is the open-source server-side header bidding engine maintained by Prebid.org, with Go and Java implementations. A host company runs it: PBS takes one OpenRTB request, fans it out to bidder adapters, and returns a merged response. This profile follows the documented /openrtb2/auction endpoint and the Go implementation, PBS-Go.

Direction and version

A client such as Prebid.js, a mobile SDK, or another server posts a request to the PBS /openrtb2/auction endpoint, and PBS returns one response that combines its bidders' bids.

OpenRTB 2.x JSON that accepts 2.5 and 2.6 fields; PBS moves 2.6 fields back to their 2.5 ext locations for bidders that only support 2.5. Prebid's own flags under ext.prebid are JSON true or false.

The RTBlint profile prebid-server checks requests and responses against the published contract.

Rules beyond the OpenRTB spec

PBS refuses wseat and bseat. A bidder only sees an impression that names it in imp.ext.prebid.bidder (or the deprecated imp.ext.{bidder}).
A stored request object in ext.prebid.storedrequest or imp.ext.prebid.storedrequest must carry a non-empty id. PBS merges the stored content into the request before the auction, so stored fields may be absent from the raw payload.
PBS-Go uses only the first currency in cur and drops the rest. A missing cur is treated as USD.
Multibid maxbids is clamped to 1 through 9. PBS-Go ignores multibid entries without maxbids or without a bidder selector.
ext.prebid.cache must ask for bids, vastxml, or both.
An alias in ext.prebid.aliases cannot map a bidder code to itself. Each key in ext.prebid.aliasgvlids must name a declared alias and carry a positive GVL ID.
Price granularity is a legacy name (low, med, medium, high, auto, dense) or a custom object with strictly increasing ranges and positive increments. PBS-Go accepts precision from 0 to 15.
bid.ext.prebid.type names the bid's media type. It must agree with bid.mtype and with a media object the impression offered.
PBS fills a missing Native request asset id from the asset's position in the array, so request assets may omit it.

Documented extensions

Path	Meaning
`imp.ext.prebid.bidder`	Bidder parameters keyed by bidder code; it also selects which bidders get the impression.
`ext.prebid.storedrequest`	ID of a stored request that PBS merges into this one.
`imp.ext.prebid.storedauctionresponse`	A stored response that replaces the live auction for the impression.
`ext.prebid.targeting`	Ad server targeting options such as price granularity and winner keys.
`ext.prebid.cache`	Server-side caching of bids or VAST XML.
`ext.prebid.aliases`	Bidder aliases mapped to their adapter codes.
`ext.prebid.multibid`	How many bids a bidder may return per impression.
`ext.prebid.currency.rates`	Custom currency conversion rates for the request.
`ext.prebid.channel`	Integration channel, such as pbjs, with a required `name`.
`user.ext.prebid.buyeruids`	Bidder user IDs keyed by bidder code.
`bid.ext.prebid.type`	Media type of the bid: banner, video, native, or audio.
`bid.ext.prebid.targeting`	Ad server targeting keys PBS generated for the bid.

What the validator checks for this profile

openrtb.profile.prebid.alias_noop PBS aliases must not map a bidder code to itself.
openrtb.profile.prebid.alias_not_declared A PBS alias GVL ID must reference a declared request alias.
openrtb.profile.prebid.cache_type_required PBS cache configuration requires bids or vastxml.
openrtb.profile.prebid.currency_truncated PBS-Go uses only the first request currency and drops subsequent entries.
openrtb.profile.prebid.media_not_offered The PBS bid marker ext.prebid.type=the field references an impression without that media object. Stored-request media cannot be resolved locally.
openrtb.profile.prebid.media_type_mismatch The PBS ext.prebid.type marker contradicts the bid's mtype.
openrtb.profile.prebid.multibid_normalized PBS-Go clamps maxbids to the supported range 1 through 9.

Validate against this contract

Open the tester with the Prebid Server profile, or run:

rtblint validate --profile prebid-server request.json