HFST ospell is a free open source spell-checker using weighted finite-state automata. It is a light-weight library for using combinations of two automata–a language model and an error model–for spell-checking and correction.
It has optional support for XML-based metadata using libxml++2 or tinyxml2. Automata compression is supported through libarchive, currently with zip format.
The API of the library is stable to support updating the shared library while keeping the automata and the plugins for enchant and LibreOffice in place. The api documentation is maintained with doxygen.
You can download the library and small demo applications from HFST’s main sourceforge site.