- trigraphs replacement
- line-slicing
- comment removal
- directives: #if, #else, #elif, #endif, #include, #define, #warning, #error
- non-standard directives: #includephp, #literal
- Object-like macros
- Function-like macros (Function-like macros in Function-like macros are not supported)
The license is 2-clause BSD. That means it's open-source and you are free to distribute, modify, sell or use in a commercial software and many others, as long as you keep the copyright.