Wiki · Concept · Last reviewed June 25, 2026

OpenRTB

OpenRTB is the IAB Tech Lab protocol family for real-time bidding: the machine language through which ad exchanges and bidders describe an impression, price it, and return a bid.

Category: Concept / Ad Tech Published: June 25, 2026 Modified: June 25, 2026 Last reviewed: June 25, 2026 Tags: OpenRTB, real-time bidding, adtech, bidstream, AdCOM, privacy

Definition

OpenRTB is an open technical specification for real-time bidding in programmatic advertising. IAB Tech Lab describes OpenRTB as the foundation of the programmatic advertising ecosystem, enabling real-time bidding on digital ads. The OpenRTB project began as the OpenRTB Consortium in 2010, with supply-side and demand-side companies working on a common API for automated trading of digital media.

The important distinction is between the market and the protocol. Real-Time Bidding is the auction pattern. OpenRTB is one standard way to represent that auction in software: bid requests, bid responses, notices, identifiers, device context, content context, regulatory signals, and extensions. A system can be OpenRTB-conformant while still raising serious privacy, consent, competition, or fairness questions.

OpenRTB 2.6 is the major 2.x version published by IAB Tech Lab in April 2022. The official OpenRTB 2.x repository now maintains the 2.6-and-later specification as a living source for non-breaking improvements, errata, new fields, objects, and enumerated values.

Mechanism

An OpenRTB transaction centers on the bid request and bid response. A publisher, supply-side platform, or exchange describes an available ad impression and sends the request to bidders. The bidder evaluates the opportunity and may return a bid with price, creative markup or creative references, deal information, notices, and related response metadata. The exchange selects a winner under its auction rules and uses notices to communicate win, billing, loss, and clearing-price information.

The 2.6 specification defines objects for impressions, sites, apps, devices, users, content, regulations, sources, deals, metrics, native placements, video, audio, and connected-TV-style inventory. It also uses companion specifications. AdCOM, the Advertising Common Object Model, keeps common object definitions and enumerated lists used by OpenRTB 2.x so values can evolve without rewriting the whole protocol. The SupplyChain Object exposes parties involved in selling or reselling a bid request.

That machinery makes the bidstream highly structured. It also makes it portable. A field that looks like implementation detail to one engineer can become targeting evidence, pricing evidence, fraud evidence, or identity evidence for another institution.

Agent Context

OpenRTB matters for AI because automated buying, fraud detection, brand safety, dynamic creative selection, and pricing systems can all treat bid requests as structured input. A bidding agent can inspect impressions, infer value, choose a price, and test policy limits before responding. A compliance agent can inspect whether a request includes sensitive context, missing consent signals, unauthorized seller paths, or identifiers that should not be present.

This does not make OpenRTB an AI safety standard. It is an ad-market protocol. Its relevance is that agentic systems inherit the affordances of the protocols they operate through. If the protocol makes device, content, location, user, and regulatory signals easy to move, the governance layer has to decide which of those signals should move at all.

Governance Use

A governed OpenRTB deployment should record the specification version, exchange endpoint, bidder endpoint, request and response schema version, auction type, data fields sent, regulatory objects, identifier objects, SupplyChain Object nodes, ads.txt authorization checks, Sellers.json resolution, retention policy, and downstream model-use limits. Sampling a few requests is not enough; the fields can vary by publisher, app, jurisdiction, deal, device, content type, and auction configuration.

Governance should also separate protocol validity from policy validity. A valid bid request may still carry excessive location precision, sensitive page context, children-related signals, inferred health categories, or persistent identifiers where contextual advertising would suffice. The audit question is not only "does this parse?" It is "why was this field sent, who received it, and what are they allowed to do next?"

Limits

OpenRTB does not prove that a seller is authorized, that a user consented, that a profile is accurate, that a segment is non-discriminatory, or that losing bidders discard data. It standardizes a transaction. Other controls are needed for authorization, minimization, privacy review, deletion, competition policy, and user-facing explanation.

The protocol can also make harmful scale feel ordinary. Once a bid request is a well-formed object, many institutions can process it quickly. That is useful for interoperability, but it can obscure the civic fact that a person reading, watching, listening, or playing may have triggered a data event in an invisible market.

Source Discipline

Claims about OpenRTB should cite the exact IAB Tech Lab source and version. The OpenRTB 2.6 PDF, the OpenRTB 2.x repository, AdCOM, SupplyChain Object materials, and OpenRTB 3.0 materials are related but distinct. Claims about real deployments require implementation evidence, logs, contracts, or regulator findings; the protocol alone does not show which fields a specific exchange sends.

Spiralist Reading

Spiralism reads OpenRTB as grammar for attention markets. It gives the auction a shared syntax, and that syntax becomes part of how people are made legible to advertisers, platforms, and intermediaries. The discipline is to inspect the grammar before it disappears into infrastructure: every field is a possible claim about a person, a context, or a value extracted from a moment of attention.

Sources

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