How do I verify a contractor license in Washington?

You can search the official Washington board portal by hand, or call TradesAPI's GET /verify endpoint with the state, license number, and trade to get back a normalized result — valid/invalid, status, expiration, and any disciplinary actions — in one request.

What contractor trades does Washington license?

TradesAPI covers these Washington trade types today: Electrical, General Contractor, Plumbing.

Is Washington contractor license data free to check?

The Washington board's public portal is free to search manually. TradesAPI adds a single normalized API across all 50 states plus DC — every new API key includes 50 free verifications.

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Washington · contractor license lookup

How to verify a contractor license in Washington

Check any Washington contractor license — status, expiration, and disciplinary history — through one normalized API, or look it up by hand on the state board portal.

Washington coverage: Operational · live status

What you can verify

Data source: Washington open data portal (daily)

Coverage: General Contractor, Electrical, Plumbing — bond + insurance + principal

Trade types

Electrical General Contractor Plumbing

City-level licensing in Washington

Some Washington trades are licensed by the city, not the state board. We also cover municipal licensing in Seattle under the same normalized schema and the same /verify call.

Trade-specific Washington lookups

Verifying one trade in particular? These guides go straight to the Washington lookup for that trade:

General Contractor →Electrical Contractor →Plumbing Contractor →

One call. The whole picture.

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

GET /verify?state=WA&license=SAMPLE-12345&trade=electrical

{
  "valid": true,
  "name": "SAMPLE CONTRACTING LLC",
  "license_number": "SAMPLE-12345",
  "trade": "electrical",
  "expiration": "05/12/2027",
  "status": "Active",
  "state": "WA",
  "disciplinary_actions": [],
  "source_url": "https://secure.lni.wa.gov/verify/",
  "cached": false,
  "checked_at": "2026-08-14T07:00:00Z"
}

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

Verify Washington licenses programmatically

# Verify a Washington contractor license with one API call
curl -H "X-API-Key: YOUR_KEY" \
  "https://www.tradesapi.com/verify?state=WA&license=SAMPLE-12345&trade=electrical"

The official Washington board portal is at https://secure.lni.wa.gov/verify/ — free to search by hand. TradesAPI wraps it (and every other state) in one API so you don't maintain 51 different scrapers.

Start verifying in minutes

Every new API key includes 50 free verifications across all 50 states + DC, plus hosted MCP access for Claude, Cursor, and any MCP-speaking agent. No credit card to start.

Start free → Read the API docs →

Frequently asked questions

How do I verify a contractor license in Washington?: You can search the official Washington board portal by hand, or call TradesAPI's GET /verify endpoint with the state, license number, and trade to get back a normalized result — valid/invalid, status, expiration, and any disciplinary actions — in one request.
What contractor trades does Washington license?: TradesAPI covers these Washington trade types today: Electrical, General Contractor, Plumbing.
Is Washington contractor license data free to check?: The Washington board's public portal is free to search manually. TradesAPI adds a single normalized API across all 50 states plus DC — every new API key includes 50 free verifications.