Efternamn.nu is a Swedish surname resource dedicated to helping people explore the history, meaning, and development of family names. Its searchable database lists more than 416,000 active surnames and presents statistics covering 1999–2025, including historical changes in the number of name bearers, current rankings, and surname trends. Visitors can search for a surname, browse names alphabetically, and explore categories such as patronymics, soldier names, noble families, farm names, nature-based names, and names brought to Sweden through migration.

The site also supports family-history research with articles, guides, and a digital archive of historical surname books and public inquiries. Its editorial content explains naming traditions, from soldiers’ adopted names to the rise of nature-inspired surnames, and offers information about Swedish naming laws. Users looking for a new surname can find inspiration in the database and historical sources. Efternamn.nu invites visitors to contribute knowledge by submitting name meanings, origins, family stories, notable people, or corrections, helping expand its collection of Swedish surname heritage.