OpenRTB

OpenRTB is the IAB Tech Lab specification that defines the JSON (or Protocol Buffers) messages exchanged between an ad exchange and a bidder in a real-time auction: the bid request describing the impression, user, device and rules, and the bid response carrying the bid and creative.

Version 2.6 was published in April 2022 and remains the base version. Since November 2022 IAB Tech Lab has shipped dated snapshots instead of numbered releases: 2.6-202211 (DOOH object, GPP string), 2.6-202303 (Refresh objects, plcmt), 2.6-202309 (acat, DurFloor, deal attributes), 2.6-202402, 2.6-202409 (EID inserter, matcher, mm), 2.6-202501 (gtax, genres), 2.6-202505 (cids) and 2.6-202606 of 11 June 2026 (realtime, firstbroadcast, discount macros) (openrtb2.x releases; IAB Tech Lab, change to OpenRTB releases). There is no OpenRTB 2.7. OpenRTB 3.0 is a separate specification with the AdCOM object model and limited adoption. IAB Tech Lab's 2026 agentic roadmap adds Protocol Buffers and gRPC mappings and wraps OpenRTB in MCP and A2A under the AAMP umbrella (IAB Tech Lab, 6 January 2026).

Example (minimal 2.6 bid request):

{ "id": "80ce30c53c16e6ede735f123ef6e32361bfc7b22", "at": 1, "tmax": 120,
  "imp": [{ "id": "1", "bidfloor": 0.50, "bidfloorcur": "USD",
            "banner": { "w": 300, "h": 250 }, "ssai": 0 }],
  "site": { "domain": "news.example", "page": "https://news.example/a" },
  "device": { "ua": "...", "ip": "203.0.113.1" },
  "user": { "eids": [] },
  "regs": { "gdpr": 1, "gpp": "DBABMA~CP..." , "gpp_sid": [2] },
  "source": { "schain": { "complete": 1, "nodes": [{ "asi": "ssp.example", "sid": "pub-1", "hp": 1 }] } } }

at, tmax, bidfloor, ssai, gdpr, gpp and schain each have their own entry.

Related: bid request, bid response, first-price auction, SupplyChain object, AAMP.

Source: IAB Tech Lab, OpenRTB 2.6 specification and openrtb2.x releases.

1. openrtb2.x releases
2. IAB Tech Lab, change to OpenRTB releases
3. IAB Tech Lab, 6 January 2026