| [Bison](http://www.gnu.org/software/bison) | Bison is a general-purpose parser generator that converts an annotated context-free grammar into a deterministic LR or generalized LR (GLR) parser employing LALR(1) parser tables. |
| [byacc](http://invisible-island.net/byacc/byacc.html) | Berkeley Yacc (byacc) is generally conceded to be the best yacc variant available. In contrast to bison, it is written to avoid dependencies upon a particular compiler. |
| [flex](http://flex.sourceforge.net/) | Flex (Fast Lexical Analyzer) is a tool for generating scanners. A scanner, sometimes called a tokenizer, is a program which recognizes lexical patterns in text. |
