Is the API Reference - Ideal Postcodes API still reachable?

Is the API Reference - Ideal Postcodes API still reachable?

No, not at the address its own documentation gives. The host declared as its server did not resolve in DNS on 2026-09-15, across 1 indexed operation. A document can look current and still name a host that no longer exists — nothing looks wrong until the call.

ERR-2026-0472

Does the API Reference - Ideal Postcodes API need an API key?

Yes for the 17 operations checked: an anonymous request was refused, on 2026-09-15. Where the document said nothing about it, this replaces a silence with an observation.

ERR-2026-1839, ERR-2026-1930, ERR-2026-1934, ERR-2026-1975, ERR-2026-2012, ERR-2026-2019, ERR-2026-2020, ERR-2026-2045, ERR-2026-2058, ERR-2026-2061, ERR-2026-2076, ERR-2026-2078

Why is my API Reference - Ideal Postcodes request rejected when I copied the example?

Because the document contradicts itself. 2 parameters in this specification declare one type and give an example, default or allowed value of another. Both statements are in the same file, so this needs no request to confirm.

ERR-2026-2239, ERR-2026-2240

Every record behind those answers

20 open records, observed 2026-09-10. Every claim below carries the command that disproves it. If one is wrong, it should be withdrawn — 121 have been across the whole registry.

credentials are required (observed) (17)

The document establishes no authentication requirement for this operation; an anonymous request is refused with 401. The requirement is now observed rather than unknown.

Check it yourself:

curl -sS -o /dev/null -w '%{http_code}\n' https://api.ideal-postcodes.co.uk/v1/emails

an example contradicts its own declared type (2)

Parameter 'uprn' (in query) declares type 'integer' and its own example is "100023336956". A caller copying it is refused.

the host no longer exists (1)

The host of the document APIs.guru names as this provider's own origin no longer resolves in DNS.

Check it yourself:

curl -sS -o /dev/null -w '%{http_code}\n' https://openapi.ideal-postcodes.dev/openapi.json

Also filed as: ideal-postcodes.co.uk. One page, because two sweeps named the same subject differently and the record that mattered was on the page nobody would open.

If a record here is wrong

Run its check. If the answer differs from what is written, say so here and it will be withdrawn — 121 already have been. A record nobody can contest is a record asking to be trusted, which is the opposite of the point.

What this page does not tell you

This is not a clean bill of health for anything not listed. The registry was built from a sample of two directories, and an operation absent from it was almost certainly never examined. Silence here means not looked at, not looked at and fine — which is the same mistake this registry exists to record in other people.

What this is

A record of defects in the public description of machine-callable operations: documents a directory claims are live and are not, hosts that no longer resolve, specifications that contradict the API they describe. It is not a ranking, not a review, and not a judgement about the service. No credential is ever sent to anything listed here.

The whole registry, machine-readable: errata.json. Index of subjects: index.html.

Built from registry errata-2026-09-10@b7cb54d3a847. If manifest.json shows a different one, this page is behind the records and should not be trusted over them.