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x-fapi-interaction-id

de facto — unregistered response reached by regulation 3 spellings

Declared by 99 providers across 31529 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-idXFAPIInteractionIdx-fapi-interaction-Id

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 (99)

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 barclays bbandt-corp bcu-bank bendigo-and-adelaide-bank beyond-bank bmo c-hoare-and-co cashplus cdr-energy chase-uk citizens-financial-group commonwealth-bank coutts coventry-building-society cynergy-bank danske-bank-uk 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

Explore

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

Work with this as data

Every header here is available over the APIs.io API and to AI agents over MCP. HTTP Headers is not yet its own endpoint on the v1 API. Reach it through catalog search and the tag graph, or the MCP server.

MCP server

One button, every client — Claude, Cursor, VS Code and the rest.

https://apis.io/mcp

Tools for http headers

3 MCP tools reach this
  • apis_io_searchSTART HERE — APIs, providers and tags for one query, each with its total.
  • resolveTurn a domain, URL or GitHub org into the provider it belongs to.
  • find_cohortsEvery scored population of providers in the catalog.
All 92 tools →

Call it yourself

curl for this page
Search the catalog
curl "https://apis.io/api/v1/search?q=x-fapi-interaction-id&limit=10"
Everything under a tag
curl "https://apis.io/api/v1/tags/x-fapi-interaction-id"

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