API documentation

Last updated: October 17, 2026.

One HTTP route per tool, JSON in and out. Look up a carrier by USDOT number, check broker authority, pull an inspection and crash summary, screen for identity linkage, or issue a dated carrier selection record. Built from FMCSA's public records.

Base URL

https://fmcsa-mcp-843680657471.us-central1.run.app/x402/<tool>

Send the tool's arguments as a JSON object in a POST body, or as query parameters on a GET (lists comma-separated). A machine-readable description of every route is at /openapi.json.

Try one now, with no account

Turn an MC number from a rate confirmation into a USDOT number. This tool is free.

curl "https://fmcsa-mcp-843680657471.us-central1.run.app/x402/find_carrier_by_mc?mc_number=MC12892"

Or use the free lookup page in your browser. With an API key and no code, run a check in your browser.

Authentication

Free tools need nothing. A paid tool accepts either of two ways to pay:

An API key with prepaid credit. Send it on every call as Authorization: Bearer fmk_... or X-API-Key: fmk_.... This is the route for teams without a crypto wallet. Request a free evaluation key ($5 of credit, reviewed by hand).
x402, USDC on Solana, Base or Polygon, paid per call with no account. A paid call without a key or payment gets an HTTP 402 stating its price. The payment flow is on For agents.

A call is charged only when it returns records. A USDOT number that does not exist, a search with zero results, or a service error costs nothing. With a key, each response carries x-credit-remaining-atomic, your balance in millionths of a dollar. An unknown or revoked key gets 401. A key with too little credit gets the normal 402, so that call can still be paid with x402.

A paid call with an API key

curl -X POST "https://fmcsa-mcp-843680657471.us-central1.run.app/x402/lookup_carrier" \
  -H "Authorization: Bearer fmk_YOUR_KEY" \
  -H "Content-Type: application/json" \
  -d '{"usdot_number": 2122247}'

Use a key from an MCP client

claude mcp add --transport http fmcsa-carrier https://fmcsa-mcp-843680657471.us-central1.run.app/mcp \
  --header "Authorization: Bearer fmk_YOUR_KEY"

In Cursor or another client that reads a JSON config:

{"mcpServers": {"fmcsa-carrier": {
  "url": "https://fmcsa-mcp-843680657471.us-central1.run.app/mcp",
  "headers": {"Authorization": "Bearer fmk_YOUR_KEY"}}}}

Endpoints

Every route is /x402/<tool>. Prices are per call in USD; see Pricing for the full table.

Tool	What it answers	Arguments	Price
`find_carrier_by_mc`	The USDOT number behind an MC, MX or FF docket, and the docket's status.	`mc_number`	Free
`screen_carrier_identity`	Whether a carrier is flagged under FMCSA's chameleon-carrier methodology, its cluster size, and a count of linked carriers with a motive signal. No member detail.	`usdot_number`	Free
`get_catalog`, `get_sample`, `get_identity_sample`	Every field and price, and free samples of real responses.	none	Free
`lookup_carrier`	One carrier's current profile: status, authority, insurance-filing flags, out-of-service orders, safety rating and its date.	`usdot_number`	$0.01
`search_carriers`	Filtered search (state, safety tier and more). Up to 100 rows per call.	`state`, `safety_tier`, `limit`, more in the catalog	$0.02
`get_safety_history`	Dated snapshots and changelog entries for a carrier.	`usdot_number`	$0.015
`get_inspection_crash_summary`	Roadside inspection, violation and out-of-service counts and rates, and the trailing 24-month crash summary.	`usdot_number`	$0.02
`check_broker_authority`	Whether a broker holds active broker authority, with its dockets and bond-filing status.	`mc_number` or `usdot_number`	$0.05
`check_carrier_identity`	Identity-linkage detail for one carrier: flag, match score, cluster size, motive counts. Never names another carrier.	`usdot_number`	$0.05
`check_address_consistency`	How many distinct business addresses and phones a carrier reports across FMCSA's independent records.	`usdot_number`	$0.01
`confirm_identity_link`	Whether two carriers you already suspect share an identity cluster.	`usdot_number_a`, `usdot_number_b`	$0.08
`check_applicant_against_roster`	Whether an applicant shares an identity cluster with anyone on your own roster.	`usdot_number`, `roster_usdot_numbers`	$0.08 + $0.01 per roster entry
`check_roster_changes`	Which carriers on your roster changed on or after a date, and what changed.	`roster_usdot_numbers`, `since`	$0.05 + $0.005 per roster entry
`get_carrier_selection_record`	One dated, SHA-256-hashed record of the public factors a broker's carrier-vetting file may cite. Not a score.	`usdot_number`	$0.10

Examples

Broker authority

curl -X POST ".../x402/check_broker_authority" -H "Authorization: Bearer fmk_YOUR_KEY" \
  -H "Content-Type: application/json" -d '{"mc_number": "MC147039"}'

Inspection and crash summary

curl -X POST ".../x402/get_inspection_crash_summary" -H "Authorization: Bearer fmk_YOUR_KEY" \
  -H "Content-Type: application/json" -d '{"usdot_number": 2122247}'

Carrier selection record

curl -X POST ".../x402/get_carrier_selection_record" -H "Authorization: Bearer fmk_YOUR_KEY" \
  -H "Content-Type: application/json" -d '{"usdot_number": 2122247}'

The record carries a SHA-256 hash of its own contents. A free link, GET /verify/<hash>, confirms that we issued exactly that record, when, and for which carrier. We store only the hash and four small facts, never the record. Read what a carrier-selection file should show.

Roster changes

curl -X POST ".../x402/check_roster_changes" -H "Authorization: Bearer fmk_YOUR_KEY" \
  -H "Content-Type: application/json" \
  -d '{"roster_usdot_numbers": [2122247, 1234567], "since": "2026-09-01"}'

Rosters take 1 to 100 distinct USDOT numbers. Over the limit is a free error, never a silent truncation.

Errors

Status	Meaning	Charged
400 `invalid_arguments`	The body says what to fix: `problems`, `expected_arguments` and a working `example`.	No
401 `invalid_api_key`	Unknown or revoked key.	No
402	Payment or enough credit needed. The response states the price and how to pay.	No
404 `not_found`	No such carrier or docket.	No
429 `rate_limited`	Over 60 requests a minute from one IP address.	No
503	The key store is unavailable. The call is never served free.	No
504 `query_timeout`	The query timed out.	No

The full list of error codes is on For agents.

What the data is, and is not

Every response states the date its records are current as of (record_as_of). Treat answers as of that date, never as live.
FMCSA stopped updating its legacy licensing and insurance archives on 2026-05-14. For about 72% of Active-authority carriers, authority and insurance-on-file fields describe that date. These carry the flag authority_status_is_legacy_li_not_motus. Confirm current authority and insurance with FMCSA or the insurer before relying on them.
"Unrated" means FMCSA has assigned no safety rating. It is not a finding that a carrier is safe or unsafe. Crash counts are a floor, because some crash records carry no USDOT number.
Identity-linkage fields are data patterns, not findings of fraud. The responses never name or point at another carrier.
The data describes regulated motor carriers as business entities. It is not a consumer report and must not be used as one. See the Terms.

Questions, or want a key? Request a free evaluation key.