Huffman is a project mainly written in PERL and SHELL, it's free.
Huffman Encoding & Decoding in 27 lines of Perl
Oh, yeah, character frequency and Huffman code table generation too.
Example usage:
file=README.md
./frequencies.pl $file > freq.txt
./huffman.pl freq.txt > huff.txt
cat $file | ./encode.pl huff.txt > enc.huf
cat enc.huf | ./decode.pl huff.txt > dec.txt
diff $file dec.txtSuck it, Trebek.