It works on the vast majority. We have near 100% coverage for large, established companies covering the majority of American employees; tiny startups is an area where we're continuing to add data sources to deliver the best results possible.
Thanks for checking it out! We use a number of different data sources (social data, Crunchbase, DNS records, email MX records, etc.) to map domain -> company and email -> individual identity.
Thanks for checking it out! Our data comes from over 250 public and private data sources, including LinkedIn, Crunchbase, email MX records, company DNS records, and more.
The confidence score is our confidence in the employment verification result—that the email address provided represents a real employee at the company that owns the domain.