Source.tid

Field facts

Path

source.tid

Object

Source

Type

string

Requirement

Recommended

Added

OpenRTB 2.5

Spec section

3.2.2

How it is used

Buyers use tid to deduplicate one impression arriving by several supply paths and to compare those paths. The party that creates the opportunity sets it once, and each hop passes it through unchanged. A refresh or a new page view is a new transaction with a new value. The core spec has no per-impression transaction ID; some stacks put one in imp.ext.tid, which is a different key.

Example

Where the field sits in a payload, with everything else left out:

{
  "id": "req-1",
  "source": {
    "tid": "0b6a3c8e-4f1d-4c2b-9e7a-5d8f1a2b3c4d"
  }
}

Common mistakes

• Each exchange minting its own tid defeats the field: the buyer sees unrelated values for one opportunity and cannot deduplicate it.
• Reusing one tid across refreshes merges separate auctions in buyer logs.
• Sending a number instead of a string is a type mismatch.

Version history

Added in OpenRTB 2.5, and present in the latest snapshot. The table shows how each version's spec text types the field.

Related fields

• Source.fd
• BidRequest.id
• SupplyChainNode.rid

Other Source fields

• ext
• fd
• pchain
• schain

For a walkthrough of the whole object, read Supply chain (schain).