API

Free public endpoints for single facts · member endpoints for scale, history and evidence

The public API is free, needs no key, and returns provenance with every response so you can cite it directly. It is rate-limited to 60 requests/minute per IP and is intended for single-entity lookups. Bulk exports, full change history, the bitemporal ledger and entity resolution are member features on the authenticated /api/v1 API — see membership.

Public API (free)

Base URL: https://numberresearch.org/api/public/v1 · Licensed CC BY 4.0 — attribute NumberResearch.org.

GET /area-codes/{npa}

Status, jurisdiction, prefix-assignment counts, thousands-block breakdown, official exhaust forecast and relief-planning flag for one area code.

curl https://numberresearch.org/api/public/v1/area-codes/626

GET /relief

The current relief-planning area code list with each NPA's latest overlay/split/jeopardy event.

GET /changes/recent

A sample (up to 50) of the last 30 days of observed numbering changes. Full field-level history is a member feature.

Every response includes a _meta object with source, source date, license and disclaimer. Machine-readable catalogs: /datasets.json · /data-sources.json.

Member API (authenticated)

Base URL: https://numberresearch.org/api/v1 · Bearer token (generate on your membership page). Professional 1,000 calls/day · Business 10,000/day.

Endpoint	Tier	Purpose
GET /area-codes/{npa}	Professional	Full area-code record
GET /assignments	Professional	Prefix & block assignments, filterable by npa/state/assignee/month
GET /events	Professional	Bitemporal change-event ledger
GET /entities/{ocn}	Professional	Evidence-based entity resolution (OCN ↔ name ↔ FRN)
GET /bulk/prefix-assignments	Business	Full snapshot export

Terms: all records are initial-assignee data — not current serving carriers (numbers may be ported). Prefix-assignment utilization is not the share of individual numbers in use. Do not redistribute member data without an OEM licence. Data originates from NANPA/CNAC/FCC public sources.