List of Java APIs

There are three types of Java Programming Language Application Programming Interfaces (APIs) :

the official core Java API, contained in the JDK or JRE, of one of the editions of the Java Platform. The three editions of the Java Platform are Java ME (Micro edition), Java SE (Standard edition), and Java EE (Enterprise edition).
optional official APIs that can be downloaded separately. The specification of these APIs are defined according to a Java Specification Request (JSR), and sometimes some of these APIs are later included in the core APIs of the platform (the most notable example of this kind is Swing).
unofficial APIs, developed by third parties, but not related to any JSRs.

Third-parties can freely implement any JSR specifications for an official API (even for the core API of the language), providing that they conform to the Technology Compatibility Kit (TCK) for this JSR (the TCK is a suite of tests that checks conformance of implementations for a JSR). The result of this freedom is that many official APIs have more implementations than the Sun's Reference implementation (RI).

The following is a partial list of Application Programming Interfaces (APIs) for the Java Programming Language.

1 Official APIs
2 Unofficial APIs (Released by third parties)
3 Notes
4 See also

Official APIs

Java Platform, Standard Edition (Java SE)

Name	Acronym	Description and Version History	Available from
Java Advanced Imaging	JAI	An API which provides a set of interfaces that support a high-level programming model allowing to manipulate images easily.
Java Communications API	JCA
Java Data Objects	JDO	A specification of Java object persistence.
JavaHelp		A full-featured, extensible help system that enables you to incorporate online help in applets, components, applications, operating systems, and devices.
Java Media Framework	JMF	An API that enables audio, video and other time-based media to be added to Java applications and applets.
Java Naming and Directory Interface	JNDI	An API for directory services.
Java Speech API	JSAPI	This API allows for speech synthesis and speech recognition.
Java 3D	J3D	A scene graph-based 3D API.	available here
Java OpenGL	JOGL	A wrapper library for OpenGL.	available here
Java Mail	(none)	A framework to build mail and messaging applications	available here
Java USB for Windows	(none)	A USB communication of Java applications	available here

Java Platform, Enterprise Edition (Java EE)

Bundled APIs (part of standard download)

Name	Acronym	Java package(s) that contain the API
Java Message Service	JMS
JavaServer Faces	JSF	javax.faces

Optional APIs (downloaded separately)

Name	Acronym	Available from
Java API for XML-Based RPC	JAX-RPC	available here

Java Platform, Micro Edition (Java ME)

Name	Acronym	Available from
Connected Limited Device Configuration	CLDC	Reference implementation is available here
Java Telephony API		available here

Unofficial APIs (Released by third parties)

This list is very incomplete, as the number of APIs available for the Java platform is overwhelming.

Rich Client Platforms

Office_compliant libraries

Apache POI

Compression

LZMA SDK, the Java implementation of the SDK used by the popular 7-Zip file archive software (available here)

Development assistance

Lady4j. Programming assistant and application server issue solver. (available here)
Cobra HTML parser and renderer library.
JScripter(short for JS) is a set of open source Java libraries and specifications. It allows Java developers to easily make large JavaScript applications.

Numerical analysis

JScience

Game engines

Real-time libraries

Javolution

Rendering libraries

Flying Saucer XML, XHTML, and CSS 2.1 rendering library.
Cobra HTML parser and renderer library.

Windowing libraries

Standard Widget Toolkit (SWT)