In addition to [Sun's JDKs|] (and their new ''Open Source Java'' project, see below), we know of the following Java or java-like implementations:

* [Blackdown's SDK|] - a linux port of Sun's JDK ([Info on license|])
* [GCJ|] and [GNU Classpath|] - a free compiler and library for producing native binary or bytecode; compatibility unknown
* [Kaffe|] (clean-room project, unknown compatibility)
* [Japhar|] (clean-room project, unknown compatibility; no change since 1998)

[ebu] - This was the result of a quick survey, short of facts. Feel free to update and amend.


See also: JVM benchmarks in [Volano Report|] 

-- [RoustemKarimov]


!! Open Source Java

Sun is now seeding open-source communities around its implementations of the Java platform. The company is releasing the code under an open-source license, and putting in place the infrastructure for a community to collaborate on a source-code commons.  Already released components includes the ~HotSpot Virtual Machine and Java programming-language compiler (javac), with complete NetBeans project metadata, with the remainder of the open-source JDK to be made available in the first half of 2007.

* [Free and Open Source Java|] (announcements, press releases, etc.)
* [Open-Source Java Project Overview|]
* [Free and Open Source Java - FAQ |]
* [Open-Source JDK project community site|]
* [OpenJDK SVN Access (code)|]