We're counting down to the last free Oracle Java 8 update - what's your plan?


Azul can save your day. Learn How!

Basic Facts about Zulu Enterprise

What is Azul Zulu Enterprise?

Zulu Enterprise builds of  OpenJDK are 100% open source Java Development Kits (JDKs) that are compliant with the Java SE standard. Zulu Enterprise subscriptions provide timely security updates, bugfixes, and multiple support options for businesses whose operations depend upon Java. Zulu Enterprise can be deployed across various operating systems, containers, hypervisors and cloud platforms. Zulu Enterprise binaries are built from the OpenJDK project sources and include backports of bug fixes and security updates after the relevant OpenJDK project no longer publishes such updates. 

What is a “certified” build of OpenJDK?

Zulu is verified compliant with the Java Standard Edition (“Java SE”) specifications using the OpenJDK Community Technology Compatibility Kit (TCK) licensed from Oracle. The TCK is a suite of more than 120,000 tests which ensures that a binary build of OpenJDK meets all the specifications of the individual JSRs for a given version of Java SE (e.g. Java 8). Azul is one of a small number of organizations and companies that licenses the TCKs for Java SE.  In addition to running the TCKs on all Zulu builds, the Zulu QA team also performs extensive testing against a wide range of application stacks and open source projects.

How are Zulu Enterprise subscriptions priced?

Zulu® Enterprise is priced on a subscription basis based upon the number of Supported Systems (desktops and/or virtual or physical servers) running Java applications. Here’s our pricing:

Max # of Supported Systems Price/Year (Standard Support) Price/Year (Premium Support)
25$12,000Not available

Your Azul Sales representative will provide pricing that matches your specific requirements and help you maximize the value of your Zulu® Enterprise Subscription.

How is Zulu Enterprise licensed?

 Zulu is licensed under GPLv2 with Classpath Exception.

What Zulu OpenJDK packages and Java versions are available?

Today, Zulu supports Java SE 10, 9, 8, 7, and 6. Azul provides free community builds of Zulu on our download page, and JDKs plus JRE bundles to Zulu subscribers. Zulu is certified on the following operating systems:

Operating SystemJDK10JDK9JDK8JDK7JDK6

Windows: Client 10, 10 IoT Core, 8.1, 8, 7; Server: 2016, 2012R2, 2012, 2008R2

Linux: RHEL, CentOS, Ubuntu, Debian, SLES, Oracle Linux, Amazon Linux, Container Linux, Alpine Linux
macOS Sierra, High Sierra 
Solaris V11, V12

Exact platforms and major versions are listed in product release notes as new versions and target types get added regularly.

What are Zulu Community Builds?

Azul makes certain versions of the full Zulu JDK freely accessible from the Zulu download site.  These “Zulu community” builds are builds of OpenJDK versions which are (currently or soon to be) available in the relevant OpenJDK project. In contrast, Zulu Enterprise builds will continue to be updated even after the relevant OpenJDK project no longer publishes such updates, and will include backports of bug fixes and security updates. 

What does Zulu Enterprise support consist of?

Azul offers a number of support options for certified Zulu Enterprise binary distributions, including security updates and backported bug fixes as well as 24×7 mission-critical support. Zulu Enterprise builds will continue to be updated even after the relevant OpenJDK project no longer publishes such updates, and will include backports of bug fixes and security updates during their support term. The Zulu product is supported by a dedicated team of engineers and QA professionals that provide tier 1, 2 & 3 support, including root cause analysis and temporary patches in addition to backporting bug fixes and security patches. Support is available both for current releases and older versions (e.g. Java 7 and 6). You can view all of Azul’s support terms at https://www.azul.com/products/azul_support_roadmap/.

Are there performance differences between Zulu Enterprise and Oracle HotSpot?

The quick answer is no. Any variation between benchmarking runs between OpenJDK and HotSpot is smaller than the variation between runs for either OpenJDK or Oracle HotSpot alone.

Does Azul offer mission-critical support for Zulu Enterprise?

Azul has a proven track record in supporting mission-critical applications within large organizations. You can view selected customer logos on our Customer Success page.

What is your product release velocity across your different Zulu Enterprise support offerings?

Zulu follows OpenJDK’s quarterly scheduled updates (i.e. OpenJDK critical patch updates or “CPUs”), and responds to any midcycle critical security update released by Oracle, Red Hat, or ourselves. Azul reviews the Common Vulnerabilities and Exposures (“CVE”) list to identify which code modules got patched, whether those lie within or outside Zulu, and, with our release notices, provide a summary of change impact. Azul also backports all changes into older versions of Java (i.e. Java 7 and 6). Due to the sensitive nature of security details, Azul only publishes the CVE details in the Zulu Enterprise release notes and provides these directly to subscribers. Zulu public user documentation does not enumerate any CVE details.

Does Azul upstream bug fixes?

Yes, Azul’s OpenJDK committers upstream all changes and bug fixes back to the OpenJDK community. 

How does Zulu accommodate Oracle and OpenJDK moving to LTS and 6-month feature releases starting with Java 9?

Starting with Java 9, Azul announced that each Java SE feature release will have a medium-term support, or long-term support designation (ie. “MTS”, or “LTS”, respectively). LTS releases occur every three years. MTS feature releases occur annually in the off-years in between LTS releases. LTS releases retain a 10-year lifecycle and all Azul products offer versions that adhere to the LTS lifecycle. MTS releases add Zulu Enterprise versions permitting the use of new features created in OpenJDK but with formal support. The goal is giving early adopters trusted support on feature releases without waiting upwards of three years for the next LTS cycle to begin.

Technical Facts

Is Zulu supported in Cloud, virtualized, or containerized environments?

Yes to all three. Azul has strategic partnerships with major ISVs and cloud providers and will support Zulu on all cloud, virtualization, or containerized platforms where the client OS is also supported.

Can I use Zulu with Eclipse?

Yes, Zulu is a fully Java SE compliant JVM and can be used with any IDE or any other development tool that supports Java SE.  

Is there any additional functionality available with Zulu?

In addition to the standard JDK, Azul ships the open source FreeType font rendering library in each Zulu JDK. Azul also makes available add-on packages, including Zulu Commercial Compatibility Kit (CCK) and the Zulu Cryptography Extension Kit, which contains extended cipher lengths policy files. The CCK contains additional functionality that is not included in the OpenJDK source, but which will help ensure compatibility in applications that take advantage of specific additional features that Oracle bundles into HotSpot. The Zulu CCK is free and can be added easily to Zulu as part of your normal software update process. Today the CCK contains Monotype™ fonts.

Is OpenJDK similar to Oracle HotSpot?

OpenJDK is the reference implementation for Java SE. HotSpot is the name of the Java Virtual Machine within OpenJDK, and gets built into the binary Oracle JDK, Oracle JRE, and other SKUs. All development by Oracle for Java 7 and later branches was and is done in the open. The only exception is security fixes, where development is done in private and source changes are only introduced into the open on specific scheduled boundaries. Oracle does add some closed source components within their HotSpot-based products, including font libraries, some of which are available from Azul in the Zulu Commercial Compatibility Kit (CCK).

What are the technical differences between OpenJDK and Oracle HotSpot?

Many closed source components that Oracle ships with Oracle JDK are compatible with OpenJDK, but are not part of the Zulu OpenJDK bundles. These include Mission Control, Flight Recorder, Visual VM, Derby DB, Java Web Start, Applets/JRE Browser PlugIn, JavaFX, Font Rendering/Fonts, Cryptography Extensions, SNMP Protocol Adapter, Color Matching, Anti-Aliased 2D Rendering, and JavaScript engine (pre 8.x). Select details are listed below.

Does Zulu have any font rendering/font differences?

Yes. Oracle ships T2K, a third party closed source font rendering library, and Monotype Lucida font files. OpenJDK depends on the Freetype font rendering library which Zulu ships in the base package. Azul also makes available relicensed copies of the Lucida fonts via the Zulu Commercial Compatibility Kit (CCK).

Does Zulu use Cryptography Extensions?

The Zulu Cryptography Extension Kit (CEK) package provides the same unlimited cipher strength as Oracle’s JCE add-on. It ships as an add-on to Zulu.

Does Zulu use JavaFX?

Java FX is an Oracle product. OpenJFX is not part of OpenJDK and is therefore not included in Zulu distributions. Persons interested in OpenJFX support should contact their Azul representative. 

Does Zulu use the Mission Control or Flight Recorder commercial features?

Not at this time. Oracle announced their plans to open source both Mission Control and Flight Recorder by late 2018. Once they appear in OpenJDK, then they each may also become available from Zulu.

Does Zulu use the SNMP Protocol Adapter?

No. The SNMP protocol adapter not part of the Java SE standard or the OpenJDK project, but Oracle does ship it in its HotSpot product. It is recommended that Zulu customers use JMX which part of the Java SE standard.

Which Color Matching library does Zulu ship?

Oracle JDK ships the third party KCMS color matching library from Kodak. OpenJDK and Zulu uses the LCMS open source color matching library.

Which Anti-Aliasing 2D rendering library does Zulu ship?

Oracle JDK 9, OpenJDK 9, and Zulu 8 and 9 include the Marlin open source library.Older Oracle releases ship the third-party Ductus anti-aliasing library. Older OpenJDK and Zulu releases use the Pisces open source rendering library.

Which JavaScript engine does Zulu ship?

Oracle JDK, OpenJDK, and Zulu for JSE 8 all ship the same Nashorn engine for running JavaScript. Oracle JDK 7 and 6 ship the Mozilla Rhino engine. Azul provides the Mozilla Rhino engine as an add on to Zulu 7. OpenJDK and Zulu 6.x are compatible with Rhino, but neither provides the engine.

Are there any technical differences between Zulu community downloads and the Zulu Enterprise or Zulu Embedded binaries shipped to customers?

Zulu community downloads are always full JDKs, targeting developer-focused use cases. Subscriber downloads may be JDKs, JREs, compact profiles, or other tailored bundles, targeting production and redistribution use cases, all in addition to application development. Also, all commercial Zulu builds, whether Enterprise or Embedded, go through Azul’s source refinement process, rendering neutral any raw OpenJDK code that could carry copyleft viral contamination normally excluded by the Classpath Exception

Useful Basic Definitions:

OpenJDK project is the open source project where new Java versions are created and older versions maintained.

Java SE is the standard (specification, reference implementation, and test suite) that an implementation must pass to be certified as Java compliant.

Zulu is Azul’s binary distribution of OpenJDK that adheres to the Java SE standard and is a compliant implementation.


© Azul Systems, Inc. 2018 All rights reserved.