Soundex is a phonetic algorithm for indexing names by sound, as pronounced in English. The goal is for names with the same pronunciation to be encoded to the same representation so that they can be matched despite minor differences in spelling.

This module implements the original soundex algorithm developed by Robert Russell and Margaret Odell, patented in 1918 and 1922, as well as a variation called "American Soundex" used for US census data, and current maintained by the National Archives and Records Administration (NARA).