Janino is a super-small, super-fast Java compiler. Not only can it compile a set of source files to a set of class files like the JAVAC tool, but also can it compile a Java expression, block, class body or source file in memory, load the byte-code and execute it directly in the same JVM. Janino is not intended to be a development tool, but an embedded compiler for run-time compilation purposes, e.g. expression evaluators or "server pages" engines like JSP.