Snapshot diff
Inspect the planned field-diff response shape. This endpoint currently returns labelled illustrative changes, not live retained diffs or signatures on changed values.
_stub: true, every change _illustrative: true). The response shape is production-final. No date is promised here for replacing the illustrative payload with retained snapshot data.Authentication
Send Authorization: Bearer <key>. The read-only sample key fnt_DEMO_PUBLIC_V1 is limited to 20 requests/minute and 100 requests/day per trusted source IP; account fnt_ keys use their configured limits. A missing or unknown key returns 401.
Request
FONTEUM_API_KEY="${FONTEUM_API_KEY:-fnt_DEMO_PUBLIC_V1}"
curl -X POST "https://api.fonteum.com/v1/snapshots/diff" \
-H "Authorization: Bearer $FONTEUM_API_KEY" \
-H "Content-Type: application/json" \
--data '{
"dataset": "nppes",
"from_snapshot": "2026-04-01T00:00:00Z",
"to_snapshot": "2026-05-01T00:00:00Z",
"fields": ["taxonomy", "addresses"]
}'dataset— required dataset id (e.g.nppes).from_snapshot/to_snapshot— required ISO 8601 timestamps or snapshot ids.fields— optional field allow-list; defaults to["taxonomy", "addresses"].
Response
In the labelled stub, a changes[] record can carry before / after values and the nullable provenance fields present in the planned shape, plus a change_type of added, removed, or modified. A summary object totals the three. Missing provenance fields must not be inferred. The machine-readable schema lives at /api/v1/snapshots/diff/_schema.json (in-repo).