From Rosetta Code
Smalltalk/X is an implementation of Smalltalk. Other implementations of Smalltalk.
Smalltalk/X is a free implementation of the Smalltalk programming language. For download, see

The Smalltalk/X package includes IDE, debugger, compilers, UI builders and many other tools.

Smalltalk/X is a "state of the art" system, with a modern generational garbage collector, incremental non-disruptive background collector for old objects. It includes a big class library with packages for XML, SOAP, database access (also NoSQL), communication protocols, web clients and servers and much more. It also includes a modern IDE which supports syntax highlighting, refactoring, code instrumentation, coverage and unit tests.

In addition to bytecode execution (which is translated just in time to machine code), it also includes a Smalltalk-to-C compiler which can be used to generate binary executables and binary class libraries without any bytecode engine and without any IDE.

Although not normally used as such, it can be executed as a scripting language with a REPL loop.

It is available for Windows, Linux and other Unix-based platforms.