SupplyChain object

The SupplyChain object (schain) is an OpenRTB object carried in source.schain that lists, in order, every seller and reseller that handled a bid request before it reached the bidder, together with a flag stating whether the list is complete.

The object has two fields: complete, "whether the chain contains all nodes involved in the transaction," and nodes, an array of SupplyChainNode objects "in the order of the chain" (OpenRTB 2.6, section 3.2.25). Each node carries asi (the SSP, exchange or wrapper domain the bidder connects to), sid (the seller's account ID, up to 64 characters), hp ("whether this node will be involved in the flow of payment," set to 1 in version 1.0), rid (the request ID issued by that seller) and optional name and domain, omitted when sellers.json covers them (OpenRTB 2.6, section 3.2.26).

Version 1.1, released for public comment on 23 June 2026 with comment to 21 August 2026, changes the scope: entities that take technical custody of a request without being paid, such as Prebid, ad servers, SSAI platforms, SDKs and wrappers, are added to the main chain with hp=0. IAB Tech Lab expects chains to get longer and recommends staged testing (IAB Tech Lab, 23 June 2026). The Trade Desk's Rob Hazan is quoted: "Longer supply chains are not automatically worse supply chains."

Example (v1.0 chain of two nodes):

"source": { "schain": { "ver": "1.0", "complete": 1, "nodes": [
  { "asi": "ssp-a.example", "sid": "pub-1001", "hp": 1, "rid": "r-77" },
  { "asi": "exchange-x.example", "sid": "ssp-a-acct", "hp": 1 } ] } }

Related: ads.txt, sellers.json, SPO, SSAI, bid request.

Source: IAB Tech Lab, OpenRTB 2.6, sections 3.2.25 and 3.2.26; SupplyChain v1.1 (June 2026).

1. OpenRTB 2.6, section 3.2.26
2. IAB Tech Lab, 23 June 2026