Frequently asked questions

How much does a call cost?

GET /v1/authority: 0.01 USDC, GET /v1/carrier-compliance: 0.012 USDC. A fixed price per call, no account and no subscription.

How do I pay?

Through the x402 protocol, in USDC on eip155:8453. A call without payment gets a 402 answer carrying the requirements in the PAYMENT-REQUIRED header; the client signs the payment and retries with the PAYMENT-SIGNATURE header. x402 clients do this on their own.

What happens on an error?

Nothing is charged. Invalid input returns 400, an unreachable official source returns 503, and the payment is settled only after a successful answer.

Can I try it without paying?

Free trial: 3 calls per day on /v1/authority, on request only: add the query parameter free_trial=1 or the header X-Free-Trial: 1. Without that signal the route always answers 402. For an IPv6 address, the caller is its /64 block, and the addresses of one /48 block share at most 9 trial calls per day. The sample at https://authority.amacunia.fr/v1/exemple is a real answer, free.

How does an agent use it?

Through the MCP server at https://authority.amacunia.fr/mcp (streamable-http transport), or through the HTTP route described in https://authority.amacunia.fr/openapi.json and https://authority.amacunia.fr/llms.txt.

Where do the data and the rules come from?

Data: five FMCSA registration datasets (Motus) on data.transportation.gov, read live: operating authority (inys-ebih), insurance on file (c5y8-a4uz), insurance history (3uet-3z4i), suspension notices (wb4f-neki), authority history (yu5v-wbh6). Public access level; no license is stated in the catalog. Only the columns needed are read; no name, address or phone number. Rules: 49 CFR 387 (the "T" sections in force), 49 U.S.C. 13901, 13905, 13906, read on eCFR and the U.S. Code on 2026-11-11. The carrier-compliance endpoint also reads the FMCSA Company Census File (az4n-8mr2), six columns only (USDOT number, MCS-150 date, record date, status, physical state, operation), and applies 49 CFR 390.19T, read on eCFR, with the FMCSA biennial update enforcement notice read on 2026-11-11. The rules in detail: https://authority.amacunia.fr/rules.

Is this legal advice?

Information only, not legal advice; it does not replace a qualified attorney. Not affiliated with or endorsed by the FMCSA, the U.S. Department of Transportation or any U.S. government agency. Not a consumer report under the FCRA: do not use it to decide on a person's employment, credit or insurance. The FMCSA's Registration Alerts page (updated October 12, 2026) names its Licensing and Insurance (L&I) system as the authoritative record of operating authority; a Federal Register notice of April 29, 2026 (2026-08334) announces its retirement in favor of Motus, without setting a date.