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Eclipse Epsilon

Epsilon is a family of Java-based scripting languages for automating common model-based software engineering tasks, such as code generation, model-to-model transformation and model validation, that work out of the box with EMF (including Xtext and Sirius), UML, Simulink, XML and other types of models. Epsilon also includes Eclipse-based editors and debuggers, convenient reflective tools for textual modelling and model visualisation, and Apache Ant tasks.

Online Playground

If you prefer not to download/install anything just quite yet, you can fiddle with EMF models and metamodels, and with some of the Epsilon languages in the online Epsilon Playground.


Download the Eclipse Installer and select Epsilon, as shown below. Note that you will need a Java Runtime Environment installed on your system. More options for downloading Epsilon (update sites, Maven) are available here.

Epsilon in Eclipse Installer

Why Epsilon?

  • One syntax to rule them all: All languages in Epsilon build on top of a common expression language which means that you can reuse code across your model-to-model transformations, code generators, validation constraints etc.
  • Integrated development tools: All languages in Epsilon are supported by editors providing syntax and error highlighting, code templates, and graphical tools for configuring, running, debugging and profiling Epsilon programs.
  • Documentation, Documentation, Documentation: More than 60 articles, 15 screencasts and 40 examples are available to help you get from novice to expert.
  • Strong support for EMF: Epsilon supports all flavours of EMF, including reflective, generated and non-XMI (textual) models such as these specified using Xtext or EMFText-based DSLs.
  • No EMF? No problem: While Epsilon provides strong support for EMF, it is not bound to EMF at all. In fact, support for EMF is implemented as a driver for the model connectivity layer of Epsilon. Other drivers provide support for XML, CSV, Simulink and you can even roll out your own driver!
  • No Eclipse? No problem either: While Epsilon provides strong support for Eclipse, we also provide standalone JARs through Maven Central that you can use to embed Epsilon in your plain Java or Android application.
  • Mix and match: Epsilon poses no constraints on the number/type of models you can use in the same program. For example, you can write a transformation that transforms an XML-based and an EMF-based model into a Simulink model and also modifies the source EMF model.
  • Plumbing included: You can use the ANT Epsilon tasks to compose Epsilon programs into complex workflows. Programs executed in the same workflow can share models and even pass parameters to each other.
  • Extensible: Almost every aspect of Epsilon is extensible. You can add support for your own type of models, extend the Eclipse-based development tools, add a new method to the String type, or even implement your own model management language on top of EOL.
  • Java is your friend: You can call methods of Java classes from all Epsilon programs to reuse code you have already written or to perform tasks that Epsilon languages do not support natively.
  • Parallel execution: Since 2.0, Epsilon is multi-threaded, which includes first-order operations and some of the rule-based languages, making it faster than other interpreted tools.
  • All questions answered: The Epsilon forum contains more than 9,500 posts and we're proud that no question has ever gone unanswered.
  • We're working on it: Epsilon has been an Eclipse project since 2006 and it's not going away any time soon.


Epsilon is licensed under the Eclipse Public License 2.0.