Embeddable Common Lisp (ECL) is a LGPL Common Lisp implementation aimed at producing a small-footprint Lisp system that can be embedded into existing C-based applications. It is able to create stand-alone ELF executables from Common Lisp code and runs on most platforms that support a C compiler. Because it compiles Common Lisp to C, it also features an FFI system, including support for inline C to be used or generated from Common Lisp. Inline C FFI combined with Common Lisp macros and custom SETF expansions yield a compile-time preprocessor.