Ragel is described as 'finite-state machine compiler and a parser generator targeting C, C++ and ASM. It can recognize byte sequences and execute code at arbitrary points in the process' and is an app in the Development category. There are four alternatives to Ragel for Linux, Mac and Windows. The best alternative is ANTLR, which is both free and Open Source. Other great apps like Ragel are Flex (Free, Open Source), textX (Free, Open Source) and Owl parser generator (Free, Open Source).
ANTLR, ANother Tool for Language Recognition, is a language tool that provides a framework for constructing recognizers, interpreters, compilers, and translators from grammatical descriptions containing actions in a variety of target languages.
textX is a meta-language for building Domain-Specific Languages (DSLs) in Python. It is inspired by Xtext. It will help you build your textual language easily. You can invent your own language or build a support for an existing textual language.