OpenRTB field reference
40 objects and 433 fields across OpenRTB 2.0 to 2.6-202606. Each field page gives the type, default, requirement, allowed values, an example, common mistakes, and the version history taken from the spec text of every release.
Bid request
The top-level request and the objects that describe who is selling and under which rules.
| Object | Fields | What it describes |
|---|---|---|
| BidRequest | 24 | BidRequest is the top-level object an exchange sends to bidders for each auction. It carries the request ID, one or more impressions in... |
| Source | 5 | Source describes where a bid request came from before it reached the exchange and which party makes the final sale decision. It sits at... |
| SupplyChain | 4 | SupplyChain records the path a bid request took from the inventory owner to the current sender: an ordered list of nodes, one per system... |
| SupplyChainNode | 7 | A SupplyChainNode identifies one system in a supply chain: the advertising system's domain, the seller account inside that system, and... |
| Regs | 6 | Regs carries the legal and regulatory signals that apply to a bid request: the COPPA flag, whether GDPR applies, the US Privacy string,... |
Impression
One slot for sale: its formats, floors, deals, and measurement signals.
| Object | Fields | What it describes |
|---|---|---|
| Imp | 23 | An Imp is one ad opportunity offered in a bid request. Each entry in BidRequest.imp carries its own id, the media types on offer (banner,... |
| Banner | 17 | A Banner describes a display slot: the sizes it accepts, where it sits on screen, and which ad types and creative attributes the seller... |
| Format | 6 | A Format is one size a banner slot accepts, given either as an exact width and height or as a scalable ratio with a minimum width. Banners... |
| Video | 37 | The Video object, at imp.video, offers an impression as a video ad slot and tells bidders what the player accepts: media types, VAST... |
| Audio | 26 | The Audio object, at imp.audio, offers an impression as an audio ad slot in music streams, broadcast simulcasts, podcasts, and similar... |
| Native | 5 | A Native object offers an impression as native: an ad assembled from parts such as a title, image, and description so it matches the... |
| Pmp | 3 | Pmp is the private marketplace container on an impression. It lists the deals the impression is available under and says whether bidding... |
| Deal | 10 | A Deal is one agreement between a buyer and a seller under which this impression may be bought. It carries the deal id both sides set up... |
| DurFloors | 4 | DurFloors sets a price floor for one range of creative durations, so a 15 second spot and a 60 second spot in the same slot can carry... |
| Metric | 4 | A Metric reports one measured property of an impression, such as recent viewability or click-through rate, so a bidder can price it before... |
| Qty | 4 | Qty states how many billable impressions one ad play represents when a screen is seen by several people at once, mainly in digital... |
| Refresh | 3 | Refresh describes how an ad slot reloads itself while the page or app stays open: what triggers each refresh, the minimum time between... |
| RefSettings | 3 | RefSettings describes one way an ad slot refreshes: the trigger, from the AdCOM Auto Refresh Triggers list, and the minimum seconds an ad... |
Where the ad runs
The website, app, or digital out-of-home screen, its publisher, and the content around the ad.
| Object | Fields | What it describes |
|---|---|---|
| Site | 18 | The Site object describes website inventory: the site's domain, the URL of the page the ad will appear on, its content categories, and the... |
| App | 18 | The App object describes inventory inside a non-browser application, which covers mobile apps and connected TV apps alike. It sits at... |
| DOOH | 9 | The DOOH object describes digital out-of-home inventory: a screen, or a group of screens, in a physical venue such as an airport terminal... |
| Publisher | 6 | The Publisher object identifies the seller of the inventory: the entity that supplies the impression to the exchange and is paid for it.... |
| Content | 35 | The Content object describes the media around the ad: the article, video, episode, song, or stream the user is consuming. It sits at... |
| Producer | 6 | The Producer object identifies who made the content, as opposed to who sells the ad space around it. It sits at Content.producer and... |
| Network | 4 | The Network object names the company that owns or licenses a group of channels, such as a broadcast network or a studio that distributes... |
| Channel | 4 | The Channel object names the specific channel or station the content is on, such as a linear TV channel, a streaming channel inside an... |
Device and user
The device, its location and user agent, and the person behind it as far as consent allows.
| Object | Fields | What it describes |
|---|---|---|
| Device | 33 | The Device object describes the hardware and software the user is on: device class, operating system, screen, network, IP address, and... |
| Geo | 14 | A Geo object describes a location. Under device.geo it is where the device is now; under user.geo it is the user's home base, such as a... |
| UserAgent | 8 | The UserAgent object carries structured browser and platform details derived from User-Agent Client Hints, at device.sua. It exists... |
| BrandVersion | 3 | A BrandVersion pairs a brand name with its version components, mirroring how User-Agent Client Hints report brands. It appears in... |
| User | 13 | The User object describes the person behind the device: the exchange's and the buyer's IDs for them, extended IDs from identity providers,... |
| Data | 5 | A Data object groups the segments supplied by one data provider, which may be the exchange itself or a third party. Arrays of them sit in... |
| Segment | 4 | A Segment is one unit of data from a provider, in effect a key and a value, such as membership in an audience or a contextual category.... |
| EID | 6 | An EID groups one or more user IDs from a single identity source, such as a universal ID provider, inside the user.eids array. It names... |
| UID | 3 | A UID holds one user identifier inside an EID, together with the type of agent it was observed on. One EID can carry several UIDs from the... |
Bid response
The bidder's answer: seats, bids, prices, markup, and notices.
| Object | Fields | What it describes |
|---|---|---|
| BidResponse | 7 | BidResponse is the top-level object a bidder returns to an exchange. It echoes the request ID, groups bids by buyer seat in... |
| SeatBid | 4 | A SeatBid groups the bids a bidder makes on behalf of one buyer seat, such as an advertiser or agency account. A bid response carries... |
| Bid | 33 | A Bid is one offer to buy one impression. It names the impression in Bid.impid, states a CPM price, and supplies the creative, either... |
Earlier names
Objects OpenRTB 2.2 named differently before 2.3 settled the current names.
| Object | Fields | What it describes |
|---|---|---|
| Regulations | 2 | Regulations is the name OpenRTB 2.2 gave to the object at BidRequest.regs, which carries the legal and regulatory signals for a request.... |
| DirectDeals | 7 | DirectDeals is the OpenRTB 2.2 name for a deal inside imp.pmp.deals. It carries the deal id, floor, currency, auction type, and the seats... |
Where the data comes from
Types, requirements, and version ranges come from object catalogs extracted from each release of the specification, the same catalogs the RTBlint validator uses. Where IAB's tagged spec file lagged its release notes, the history follows the release notes. Definitions are written for this site; the specification versions page links the official text.