National DataBase (NDB.com) is an online directory and information-search service that says it has served the public since 1994. Its tools help users look for people and contact details across the United States, including searches by name, phone number, email address, or street address. Reverse phone and email searches are presented as ways to identify the person associated with a number or email, while reverse address searches can provide available property and household information.

NDB also offers background-check and public-record searches. Its listed report information may include current contact details and address history, relatives and household members, criminal records, bankruptcies, liens, judgments, age and date of birth, property records, and business or professional listings. Additional search categories shown on the site include police records, social media, classmates, inmates, sex offenders, vital records, census information, and work information. The service is designed for people seeking to reconnect with someone, identify an unknown caller, or research publicly available information. NDB provides site sections for terms, frequently asked questions, privacy, and member access.