Soundex - Version 1.0 The Soundex code is an indexing system which translates names into a 4 character code consisting of 1 letter and 3 numbers. It was developed so that you can find a surname even though it may have been recorded under various spellings. So indexing by Soundex will group names by sound rather than the exact spelling. I've written a freeware program that will give you all the codes for your family tree.