| J2EE | Java 2 Enterprise Edition |
| J2SE | Java Level 2 Standard Edition |
| JAAS | Java Authenticationand Authorization Service |
| JADE | Joint Audio Decoder Encoder |
| JAR | Java Archive |
| JAXP | Java API for XML |
| JAXR | Java API for XML Registries |
| JDBC | Java Database Connectivity |
| JDP | Joint Development Program |
| JEDEC | Joint Electron Device Engineering |
| JEIDA | Japanese Electronic Industries Development Association |
| JESSI | Joint European Submicron Silicon |
| JFET | Junction field effect transistor |
| JFIF | JPEG/JPG compliant image format |
| JIC | Joint Industrial Council |
| JIT | Just-In-Time |
| JJT | Josephson Junction Transistor |
| JMS | Java Message Service |
| JPEG | Joint Photographic Expert Group |
| JPG | JPEG/JFIF compliant image format |
| JQP | Josephson Quasi Particle |
| JSNM | Japan Society of New Metals |
| JSP | JavaServer Pages |
| JTA | Java Transaction API |
| JTAG | Joint Test Action Group (part of IEEE) |
| JVM | Java Virtual Machine |
