parboiled is an open-source Java library released under an Apache License. It provides support for defining PEG parsers directly in Java source code.^[2][3]

parboiled is commonly used as an alternative for regular expressions or parser generators (like ANTLR or JavaCC), especially for smaller and medium-size applications.

Apart from providing the constructs for grammar definition parboiled implements a complete recursive descent parser with support for abstract syntax tree construction, parse error reporting and parse error recovery.