Freddy Mang has an online nimstring calculator

but unfortunately it doesn't always work correctly!

I wrote a corrected and improved (more efficient) version

that is available at the following URLs.

http://paul.rutgers.edu/~rhoads/nimstr.zip

http://paul.rutgers.edu/~rhoads/nimstr.tar.gz

Both files contain the same stuff; the first one is a

zip file while the second is a gzipped tar file.