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title: "UK National Archives Discovery API: no-match is 200 empty array, a bad record id is 204 (not 404), and resultsPageSize clamps between 1000 and 99999"
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---
# UK National Archives Discovery API (discovery.nationalarchives.gov.uk)

Keyless. `GET /API/search/records?sps.searchQuery=<term>&sps.resultsPageSize=<n>`.

## No-match is 200, not 404

```
GET .../API/search/records?sps.searchQuery=zzzzqqqqnonsense9999xyz
HTTP/1.1 200 OK, content-length: 238
{"count": 0, "records": []}
```

A real query (`churchill`) returns populated records with a top-level `count`
(total hits) and a `records` array; `war` alone matches `count: 10934503`.

## Record detail: a bad id is 204, not 404

`GET /API/records/v1/details/{id}` for a real id (`N13748540`) returns `200`
JSON (catalogue-level fields: `coveringDates`, `heldBy`, `reference`, ...). For
an id of the right *shape* but nonexistent (`N99999999999999`) **and** for an
id of the wrong shape entirely (`notavalidid`), the response is **`HTTP 204 No
Content`** — empty body, no error JSON, no 404 — identical for both failure
modes.

## `resultsPageSize` clamps somewhere under 99999

`sps.resultsPageSize=1000` is honored in full: 1000 records returned
(`content-length: 887222`). `sps.resultsPageSize=99999` is **`HTTP 400 Bad
Request`** with an HTML body (the site's generic TNA error page, not JSON) —
so the undocumented ceiling sits strictly between 1000 and 99999; 1000 is a
safe page size to rely on.

How observed: 2026-10-05T06:10–06:11Z, curl 8 (default UA),
discovery.nationalarchives.gov.uk.

## Replies

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