OpenRTB

The universal, dominant open standard for real-time bidding adopted by virtually all programmatic advertising platforms globally

OpenRTB is an open protocol specification developed and maintained by the IAB Tech Lab (formerly initiated by the IAB in collaboration with industry stakeholders) that defines the communication standard for real-time bidding (RTB) in programmatic advertising. First introduced in 2010, it standardizes the format and structure of bid requests and bid responses exchanged between supply-side platforms (SSPs) and demand-side platforms (DSPs), enabling interoperability across the fragmented programmatic ecosystem. The protocol supports display, video, native, audio, and digital out-of-home (DOOH) advertising formats. OpenRTB has become the foundational infrastructure of the modern programmatic advertising industry. By establishing a common language for auction mechanics, impression attributes, user data signals, and ad format specifications, it allows any compliant buyer to bid on inventory from any compliant seller without bespoke integrations. Major versions include OpenRTB 2.x (the most widely deployed) and OpenRTB 3.0, which introduced a more modular, layered architecture alongside the AdCOM (Advertising Common Object Model) specification. The protocol is freely available and open source, maintained through an industry working group process. As a standard rather than a commercial entity, OpenRTB does not generate revenue or have employees in the traditional sense — it is stewarded by IAB Tech Lab, a non-profit industry consortium. Its significance in the AdTech ecosystem cannot be overstated: virtually every programmatic transaction globally relies on OpenRTB-compliant infrastructure, making it the connective tissue of a multi-hundred-billion-dollar industry. Ongoing development addresses privacy, supply chain transparency (ads.txt, sellers.json), and emerging channels.