You can’t start until you know what you’ve got.
Accelerate migration and derisk legacy technology replacement.
Ensure Java licensing and security compliance.
Enterprises are migrating because Oracle changed to a per-employee pricing model in January 2023 that disconnects license cost from actual Java usage. A 100-person company with two quad-core servers and 100 Java desktops typically sees a 328% price increase. A 25,000-employee company with minimal Java deployments can face bills exceeding $2 million per year. The 2026 State of Java survey found that 81% of companies have migrated, are migrating, or plan to migrate from Oracle Java to an open-source alternative.
For server applications, migration is straightforward: install the new OpenJDK distribution, update JAVA_HOME, and restart your application. 99% of server applications work correctly on the first attempt. Edge cases are almost exclusively limited to legacy desktop technologies — Java applets, Java Web Start, and JavaFX on JDK 8 or earlier. Azul has completed hundreds of enterprise migrations with a 100% success record.
From JDK 11 onward, Oracle JDK and OpenJDK are built from identical source code. Both derive from the OpenJDK open-source project. The differences are in licensing terms, commercial support offerings, update schedules, and a small number of optional bundled components that existed prior to JDK 11 (JavaFX, Java Web Start, the Java plug-in). For server-side applications on JDK 11 or later, there is no functional difference.
No. Java’s “write once, run anywhere” guarantee means the same bytecodes will execute identically on any TCK-certified JVM of the same Java version. No recompilation is needed when switching distributions. Even when moving to a newer Java version, recompilation is rarely required due to Java’s strong backward compatibility.
The Java Technology Compatibility Kit (TCK) is a suite of nearly 150,000 tests that verify a Java distribution correctly implements the Java SE specification. TCK certification is the technical guarantee that two distributions of the same Java version are functionally interchangeable. Always choose a TCK-certified distribution. Non-certified distributions cannot claim Java SE compatibility and do not carry the IP protections of the Java specification.
On 23 January 2023, Oracle replaced its processor-count and named-user pricing with a per-employee model under the Oracle Java SE Universal Subscription. Unlike typical per-employee SaaS pricing, Oracle’s model is disconnected from actual Java usage. Every employee at the organization counts toward the license cost, regardless of whether they use Java. This caused price increases of 300–400% for most organizations and triggered widespread migration to OpenJDK alternatives.
A Critical Patch Update (CPU) is a stabilized, security-only JDK update containing only security patches, not bug fixes or enhancements. A Patch Set Update (PSU) contains everything. Since the end of free Oracle JDK 8 updates, there has been at least a 25% chance per quarter that a PSU introduces a regression. CPUs allow organizations to apply security patches without this regression risk. Only Oracle and Azul provide CPU format updates for OpenJDK.
Key factors: (1) TCK certification for all binaries; (2) support for your Java versions — only Azul supports JDK 6 and JDK 7; (3) availability of both CPU and PSU format updates — only Oracle and Azul provide CPUs; (4) update speed — leading providers release binaries within one hour of the embargo lifting; (5) platform coverage for your OS and CPU architectures; (6) GPL contamination indemnification if required.
Yes. Azul is the only OpenJDK provider that still offers commercially supported builds of JDK 6 and JDK 7, including backported security patches. Oracle stopped extended support for JDK 6 in October 2018 and for JDK 7 in July 2022. For organizations that cannot yet migrate these versions, Azul Core provides security-patched builds with full commercial support.
OpenJDK is licensed under GPLv2 with a Classpath Exception (CPE). The CPE prevents the GPL’s copyleft provisions from applying to applications that use the JDK. However, if any file in a distribution that requires the CPE is missing it, and your application makes direct API calls to that file, your application code could be subject to GPL obligations — requiring you to release your source code. Some commercial providers scan their distributions for this risk and provide contractual indemnification against it.
