Google Places API handles the search layer. Verified businesses with addresses, phone numbers, websites, ratings. From there I scrape homepages, /contact, and /about pages in parallel looking for actual email addresses.
The biggest lever turned out to be query expansion. A basic search like "electricians in Michigan" tops out around 60 Google results. But if you auto-expand into every major city in the state, try synonyms (electrical contractor, electrical service, etc.), and use an LLM to generate more variations when you're still short, you can pull 500+ unique businesses from the same starting search.
Email validation was way more painful than I expected. Without it you end up with phone numbers glued to emails, URL-encoded junk, placeholder addresses like example[@]mysite.com. Took something like 15 different validation rules before the output was consistently clean.
I appreciate any feedback.