Eclipse Xtext is described as 'Xtext is an open-source framework for developing programming languages and domain-specific languages (DSLs)' and is an app in the Development category. There are three alternatives to Eclipse Xtext for Linux, Mac and Windows. The best alternative is JetBrains MPS, which is both free and Open Source. Other great apps like Eclipse Xtext are ANTLR (Free, Open Source) and textX (Free, Open Source).
JetBrains MPS is a metaprogramming system which is being developed by JetBrains. It implements language-oriented programming. MPS is an environment for language definition, a Language Workbench, and integrated development environment (IDE) for such languages.
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.