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Tracing & Correlation

x-fapi-interaction-id

de facto — unregistered response reached by regulation 3 spellings

Declared by 95 providers across 19977 published specification files in the APIs.io network.

What this header is for, and how to use it →

A count here is providers whose published contract declares this header — not providers who send it. Response headers set at the edge rarely appear in an OpenAPI at all, so a low number can measure documentation practice rather than deployment.

Spelled 3 ways

HTTP field names are case-insensitive (RFC 9110 §5.1), so every spelling below is the same header on the wire. A contract is not the wire: generated clients key off the string, and a developer reading two of these sees two different headers.

x-fapi-interaction-idx-fapi-interaction-IdXFAPIInteractionId

Reached by regulation

Basis: mandated. The law, or a technical standard the law makes binding, names this header. Only a credentialed caller can observe it in flight — the catalog can see a contract declare it, not a deployment honour it.

psd2 cma-open-banking-order consumer-data-right

Carried by the fapi standard.

Providers declaring it (95)

aemo aer agl-energy aldermore alex-bank algbra alinta-energy allica-bank amp-bank anz australian-military-bank australian-unity-bank auswide-bank avenue-bank bank-australia bank-first bank-of-ireland-uk bank-of-melbourne bank-of-queensland bank-of-scotland bank-of-sydney bank-of-us banksa bankvic bankwest bcu-bank bendigo-and-adelaide-bank beyond-bank bmo c-hoare-and-co cashplus cdr-energy chase-uk commonwealth-bank coutts coventry-building-society cynergy-bank defence-bank energy-queensland energyaustralia first-direct gateway-bank gb-bank gc-mutual-bank great-southern-bank greater-bank hampden-and-co hsbc-australia hume-bank imb-bank ing-australia investec jp-morgan-chase judo-bank keycorp kroo lean-technologies lloyds-banking-group macquarie-bank monument-bank move-bank mystate-bank national-australia-bank natwest newcastle-permanent open-banking-uk origin-energy paragon-bank people-first-bank pn-bank police-bank powershop qudos-bank rabobank-australia racq-bank recognise-bank red-energy regional-australia-bank revolut santander-uk secure-trust-bank shawbrook-bank simply-energy st-george-bank summerland-bank suncorp-bank tandem-bank teachers-mutual-bank ubank unity-bank up-bank vanquis-banking-group westpac yorkshire-building-society zopa

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All headers Tracing & Correlation Guidance on headers.apievangelist.com