javax

javax is a namespace in the Java platform that contains a broad set of APIs historically treated as extensions to the core Java API. The packages under javax cover user interface components, XML processing, data access and persistence, naming and directory services, networking, security, and various enterprise technologies. While java.* contains the core language and standard library, javax.* includes APIs that were originally envisioned as optional features or part of enterprise specifications, such as Swing for GUI, XML parsers, JNDI for naming, JDBC extensions, and enterprise APIs.

The origin of javax dates to the early Java platform when developers were encouraged to use extension libraries outside the core runtime. Over time many javax APIs became standard in Java SE or Java EE and were distributed with the JDK. In the late 2010s, Java EE was moved to the Eclipse Foundation and renamed Jakarta EE; new platform versions migrated EE APIs from the javax.* namespace to jakarta.*. Existing code that targets javax.* remains common for older versions, but new development in Jakarta EE uses jakarta.*. The javax namespace thus serves as a historical and compatibility reference within the Java ecosystem.

Notable subpackages include javax.swing for GUI widgets; javax.xml and its related packages for XML processing; javax.sql and javax.persistence for data access and persistence; javax.naming for naming and directory services; javax.net and javax.security for networking and security; and javax.imageio for image input/output.