Verify a plumber licence in California

Check a plumber's licence in California by number or by business name and get one normalized JSON record back, sourced from the Contractors State License Board (CSLB). The Contractors State License Board extract holds 18,193 records under these classifications as of 2026-08-05.

Try a free lookup — no signup, right here on this page. For programmatic access, take a free API key — 250 requests a month, no card. Also on RapidAPI and, if you would rather not write code at all, the Apify Store.

Which CA classifications count as plumbers

C-36 — Plumbing Contractor 18,193 records

A record's classifications array carries these codes, so you can tell a licence that covers the work from one that merely exists.

Run it

curl "https://contractor-license-verification2.p.rapidapi.com/v1/licenses/CA/1000016" \
  -H "X-RapidAPI-Key: YOUR_KEY" \
  -H "X-RapidAPI-Host: contractor-license-verification2.p.rapidapi.com"

1000016 is a real CA licence (STEALTH LEAK SPECIALISTS INC) in this trade, so that call works as written.

What Contractors State License Board does not publish

Disciplinary actions
General liability insurance

Full coverage detail, including the caveats that apply to every California lookup, is on the California page.

Other trades in California

General contractor Electrician HVAC contractor Roofing contractor Painting contractor

Plumbers in other states

Connecticut Florida Texas

The API is on RapidAPI with a free tier: Contractor License Verification. It is also on the Apify Store: Contractor License Lookup & Verification. Full schema at /docs.