A friend of mine recently put out a call for help, looking for open-source spell checking APIs. I knew of a few, so I've assembled a list here.
- GNU Aspell The most widely used open-source spell checker that I know of. Supersedes Ispell apparently.
- Hunspell Used by Firefox 3, OpenOffice.org and Google. It's been ported, or had bindings written, for many languages include Java
- JaSpell I thought this was a Java port of Aspell, but it doesn't mention Aspell, so it must be original.
- Jazzy A Java implementation of Aspell's algorithms. Interesting article about it here.
- After the Deadline I think this is also online based, but there's a Python library. Does a lot more than just spell checking: take a look at the page for more info.