JSLibs
- Standalone JavaScript development environment; goal: turn JavaScript into a general-purpose scripting language. Has set of native modules that contain many general-purpose classes and functions. Open source, GPL.
- http://code.google.com/p/jslibs/

Sun Labs Lively Kernel
- Web programming environment, by Sun's Project Flair. Goal: give web programming equal simplicity, generality, flexibility as used in desktop programming for 30 years, but without installation, upgrade issues of desktop programs. FAQ, forums, interactive t
- http://research.sun.com/projects/lively/

SEE: Simple ECMAScript Engine
- A small C library that provides a JavaScript parser and runtime environment, conforming to ECMAScript Edition 3 and JavaScript 1.5, and with compatibility modes for JScript et al. [Open source, BSD-style licence]
- http://www.adaptive-enterprises.com.au/~d/software/see/

DMDScript
- Implementation of ECMA 262 scripting language; standalone and ActiveScript versions available. By Digital Mars.
- http://www.digitalmars.com/dscript/

deployZone
- Cross-platform e-mail, database and web server, supports Server-side JavaScript to build Internet applications in an object-oriented, web-based content management system.
- http://www.deployzone.com/

Rhino - JavaScript for Java
- An open-source implementation of JavaScript written entirely in Java.
- http://www.mozilla.org/rhino/