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How to verify plumbing contractor licenses, in any state

Verify plumbing contractor licenses — status, expiration, and disciplinary history — across 16 states plus DC through one normalized API. Pick a state below, or call /verify with the state, license number, and trade=plumbing.

States where we verify plumbing contractor licenses

City-level plumbing contractor licensing

Some plumbing contractor licenses are issued by the city, not the state board. We cover these municipal boards under the same normalized schema:

One call. The whole picture.

The /verify response is identical in shape across every state, so your integration code never changes per jurisdiction:

{
  "valid": true,
  "name": "SAMPLE CONTRACTING LLC",
  "license_number": "SAMPLE-12345",
  "trade": "plumbing",
  "expiration": "05/12/2027",
  "status": "Active",
  "state": "AL",
  "disciplinary_actions": [],
  "source_url": "https://genconbd.alabama.gov/database-sql/roster.aspx",
  "cached": false,
  "checked_at": "2026-06-22T05:14:00Z"
}

Example response showing the normalized schema. Wire it up against deterministic fixtures in the sandbox — no credit cost.

Frequently asked questions

How do I verify Plumbing Contractor licenses?

Call TradesAPI's GET /verify with the state, license number, and trade=plumbing to get a normalized result — valid/invalid, status, expiration, and any disciplinary actions — in one request. The same call works across all 17 covered jurisdictions.

Which states can I verify Plumbing Contractor licenses in?

TradesAPI verifies plumbing contractor licenses in 16 states plus DC today: Alabama, Arkansas, Colorado, Connecticut, Delaware, District of Columbia, Idaho, Indiana, Maine, Michigan, New Hampshire, New Jersey, Oklahoma, South Dakota, Texas, Vermont, Washington.

Is Plumbing Contractor license data free to check?

Each state board's public portal is free to search by hand. TradesAPI adds one normalized API across every covered state — every new API key includes 50 free verifications.