Levenshtein is a project mainly written in C and RUBY, it's free.
fast string edit distance computation, using the Damerau-Levenshtein algorithm
The levenshtein module implements fast Damerau-Levenshtein edit distance computation in O(n) memory and O(n^2) time, using a C wrapper.
USAGE:
@install git clone git://github.com/esdras/levenshtein.git cd levenshtein rake compile rake install
@usage require 'levenshtein' Levenshtein.normalized_distance("string 1", "string 2") Levenshtein.normalized_distance([2, 3, 4, 5], [1, 2, 3, 4])