---
title: "Cross-walk an industry classification code across the four..."
method: GET
path: "/api/class/industry-resolve"
tags: ["class"]
---

# Cross-walk an industry classification code across the four...

`GET /api/class/industry-resolve`

## Request

- Base URL: `https://2s.io`
- URL: `https://2s.io/api/class/industry-resolve`
- Auth: API key in header `PAYMENT-SIGNATURE`

Cross-walk an industry classification code across the four major systems: NAICS <-> SIC <-> ISIC Rev.4 <-> NACE Rev.2. Pass the system + code and get the equivalent code(s) in every other system, with official titles where available, plus the vintage of each table used. The deterministic join that lets a KYC, procurement, ERP, or cross-border-reporting agent translate "what industry is this" between the US (NAICS/SIC), international (ISIC), and EU (NACE) standards. Backed by bundled public-domain Census concordances (NAICS<->SIC: 1997 NAICS <-> 1987 SIC; NAICS<->ISIC: 2012 NAICS <-> ISIC Rev.4) and the UNSD ISIC Rev.4 <-> NACE Rev.2 correspondence. Multi-hop links (e.g. SIC->NACE via NAICS->ISIC) are derived and explicitly flagged in notes. SIC is a retired US system; there is no newer NAICS<->SIC table.

## Query parameters

- `system` 'naics' | 'sic' | 'isic' | 'nace', required
- `code` string, required
- `trial` 1

## Other responses

- `200` (unresolved $ref)
- `400`: Invalid request — not charged. error.code: BAD_REQUEST or INVALID_PARAM (parameter validation; error.details.issues lists each problem), MALFORMED_JSON, or a request-specific code. Other client errors: 405 METHOD_NOT_ALLOWED (wrong verb; see the Allow header), 413 PAYLOAD_TOO_LARGE.
- `402`: Payment required. Body is the x402 PaymentRequirements envelope with a multi-network accepts array; the per-call price is in accepts[].amount (and on the operation as x-2s-price). Sign for whichever rail you hold USDC on (EIP-3009 for Base, partial SPL transfer for Solana) and retry with the PAYMENT-SIGNATURE header (X-PAYMENT also accepted for v1 clients). Also PAYMENT_SETTLE_FAILED (error envelope) when a verified payment failed to settle: error.details.chargeStatus is "not_charged" (retry with a fresh payment) or "unknown" (the authorization may still settle before its deadline — check it before retrying).
- `404`: Not found — NOT_FOUND (or NO_SOURCES / NO_OPINIONS): the requested entity does not exist. Not charged.
- `429`: Too many requests — RATE_LIMITED: our per-IP / per-payer limiter. Not charged; retry after Retry-After.
- `5XX`: Server-side failure. 500 INTERNAL: unexpected error; quote error.errorId (also the X-2s-Error-Id header). 502 UPSTREAM_UNAVAILABLE (or another UPSTREAM_* code): the data provider failed — composite endpoints refuse unbilled when every source fails. 503 SERVICE_PAUSED: endpoint paused by the operator kill switch, retry after Retry-After; 503 SPEND_CAP: daily upstream budget exhausted. 504 UPSTREAM_TIMEOUT. Not charged.

---

[API](https://skmtc.dev/2s-io/apis/2s-the-most-everything-api.md) · [All operations](https://skmtc.dev/2s-io/apis/2s-the-most-everything-api/llms.txt) · [OpenAPI document](https://skmtc.dev/2s-io/apis/2s-the-most-everything-api/revisions/da4c5caf686e?raw)