How to get a list of licensed contractors

1. The state's license lookup

Nearly every licensing state has a search page for checking one contractor. It's free and authoritative, and it's the right tool for verifying a license. It isn't a list: you search one name at a time, and many of these sites don't allow automated collection, so read the terms first.

2. A bulk file from the state

Some states publish their licensees as a downloadable file or through an open-data portal. This is the best free source when it exists. Expect each state to use its own columns and class codes, and expect to do the work of working out which rows are new yourself, since most files are a snapshot of everyone currently licensed.

3. A public-records request

Where no file is published, a written request to the licensing board under the state's open-records law can get you one. Ask for the fields you need and for a cost estimate. Replies can take weeks, some agencies charge for staff time, and a few limit requests from outside the state.

Some states also restrict what you can do with the result. Washington bars using lists of individuals for commercial purposes (RCW 42.56.070), and Idaho and South Carolina have similar limits on solicitation. Ask for business records where that applies, and check with a lawyer for your use.

4. A data provider

A provider does the collection and standardizing for you. The questions worth asking are the ones that separate a useful list from a stale one:

• How often is it updated: daily, weekly or quarterly?
• Does it come from licensing records, or was it compiled from the web?
• How does it decide a license is new, and do renewals count?
• Which states are complete, and which are only part-covered?
• What share of rows actually has a phone or an email?

Which should you use?

For one license, use the state's lookup. For one state once, look for its bulk file first. If you sell to contractors across several states all year, the time you'd spend standardizing and comparing files each week is usually worth more than a subscription.