Eclipse Ceylon is a modern statically-typed programming language for the Java, Android, and JavaScript virtual machines. The language features a unique and uncommonly elegant static type system, a flexible and very readable syntax, a powerful module architecture, a modular SDK, smooth interoperation with native Java and JavaScript, and with Maven and npm, excellent command-line tooling, and a full-featured IDE.

The Ceylon language is defined by a complete, but very readable specification.

Development of Ceylon ramped up in 2011, with the first major release 1.0 in 2013. Ceylon 1.1 was released in 2014, 1.2 in 2015, and 1.3 in 2016. Ceylon has a very active user community, with most interaction occurring in the various Gitter channels associated with the project.

The Ceylon project has already significantly advanced the state of the art in the Java/C# language family, and in the field of statically-typed languages in general. Innovations seen first in the Ceylon project are already being adopted in the type systems other new programming languages. Ceylon was the first language to demonstrate practical applications of free-form union and intersection types, and alerted the programming language community to the importance of these constructs. Ceylon was also either the first language, or at least one of the first two languages, to feature flow-sensitive typing, a concept which has now been adopted by a number of other languages. Furthermore, Ceylon has the most sophisticated and cleanly-integrated module system of any programming language.