Basic Facts about Zulu^®and Zulu Enterprise™

Where can I find builds of Java 12?

You can download  Zulu Community builds of OpenJDK 12 for Windows, Linux or macOS here.

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, bug fixes, and Premium and Standard 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?

All Zulu builds of OpenJDK are 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 does Zulu Enterprise stack up against other OpenJDK support alternatives?

We have been shipping free community builds of OpenJDK since 2014, along with Zulu Enterprise support subscriptions for operations that need the security of a tier-1 SLA. Sun and Oracle have historically done a great job delivering timely security updates on both a quarterly and as-needed basis. Our goal is to continue to deliver cutting-edge OpenJDK updates and support coupled with key technologies like JDK Mission control, Flight Recorder, and OpenJFX.

Want to see how Zulu stacks up against other free (and commercial) builds of OpenJDK?

Start with this one-page table.

Your Azul representative can help you make a choice that fits your operational requirements.

How are Zulu Enterprise subscriptions priced?

Zulu Enterprise is priced on a subscription basis based upon the number of systems supported.

For support on Servers (virtual and/or physical servers), the following pricing applies:

For support on Desktops (desktop or laptop computers), the following pricing applies:

For quantities greater than those shown in the tables above, the following pricing applies:

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 identically to OpenJDK, which is under GPLv2 with Classpath Exception, in addition to other third-party licenses.

What Zulu OpenJDK packages and Java versions are available?

Today, Zulu supports Java SE 11, 10, 9, 8, and 7. Azul provides free community builds of Zulu on our download page and JDKs plus JRE bundles to Zulu Enterprise subscribers. Zulu is certified on the following operating systems:

My company is still running Java SE 6.  Can you help me?

Contact Azul Sales to discuss your Zulu Enterprise support options for OpenJDK 6.

Further detail on Zulu supported platforms can be found at https://www.azul.com/products/zulu-enterprise/supported-platforms/. Exact platforms and major versions are listed in product release notes as new versions and target types get added regularly.

Does Zulu Enterprise support desktops?

Absolutely! See the table above for some examples of the various client operating systems that Zulu Enterprise supports, including Windows and macOS.

My software vendor says they support Oracle Java and OpenJDK.  Does that mean their products will run on Zulu?

Yes.

Zulu is OpenJDK. Here’s a sample version string from a recent build:

Does Azul support OpenJFX?

Yes! You can get builds of Zulu with OpenJFX for OpenJDK 8 and OpenJDK 11 from the Zulu Community download page.

Does Azul support Java Web Start (JNLP) and/or Applets?

No. These proprietary desktop technologies are no longer incorporated in the Java SE platform and have never been part of OpenJDK. Azul will work with you to identify strategies for addressing applications that depend upon Java Web Start.

What are Zulu Community Builds?

Azul has been shipping tested, certified builds of OpenJDK for more than five years, updated on a quarterly cadence. These builds of OpenJDK are free to download and use without restrictions and are available for a wide variety of OS platforms and binary distributions, including access to Zulu repos. All Zulu Community builds are freely accessible from the Zulu Community download site. These “Zulu community” builds are builds of OpenJDK versions which are available in the relevant OpenJDK project.

Subscribers to Zulu Enterprise have access to the industry’s best commercial builds of OpenJDK and include SLA-driven backports of bug fixes and security updates.

All Zulu Community builds pass the TCK for their version of Java SE, and Community builds get quarterly security updates and bug fixes in line with the mainstream OpenJDK project.

What does Zulu Enterprise support consist of?

Azul offers a variety of support capabilities for certified Zulu Enterprise binary distributions, including security updates and backported bug fixes as well as 24x7x365 live 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 the supported lifecycle. 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). 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 variations observed when benchmarking Zulu (OpenJDK) vs. HotSpot is typically the same as variations found comparing multiple runs using the same JVM.

Does Azul offer mission-critical support for Zulu Enterprise?

Azul has a proven track record in supporting mission-critical applications 24x7x365 for the world’s largest companies globally. You can view selected Azul customer logos on our Customer Success page. Our support team is geographically and globally dispersed and are experts in Java deployments and triaging JVM/JDK-related issues.

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 updates released by Oracle or other contributors to OpenJDK such as Azul and Red Hat. Azul reviews the Common Vulnerabilities and Exposures (“CVE”) list for a given security update to identify which code modules have been modified, whether those are relevant for Zulu, and, with our release notices, provide a summary of change impact. Azul also backports bug fixes and security updates made to newer versions of Java (e.g. Java 11) to older versions of Java (i.e. Java 8 and 7). 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 Zulu Enterprise include CPU and PSU updates?

Yes. Only Oracle and Azul provide quarterly PSU and CPU updates as part of their commercial support offerings. To learn more about what differentiates OpenJDK CPU and PSU updates and why they matter, read this Azul blog post. 

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 selected Java SE feature releases will have a medium-term, or long-term support designation (i.e. “MTS”, or “LTS”, respectively). LTS releases occur every three years. MTS feature releases are odd-numbered versions of OpenJDK that are shipped between LTS releases. Releases designated as LTS have a 10+-year support lifecycle, and those designated as MTS have 18-month support lifecycles that extend beyond the introduction of the next LTS release. Zulu’s MTS releases allow for the use of new features created in OpenJDK and 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. JDK 13 and 15 are the next MTS releases, and JDK 17 is the next LTS release after JDK 11.

Technical Facts and Compatibility with Oracle HotSpot

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 any supported client OS runs.

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 with each Zulu JDK. Azul also makes available add-on capabilities that are included in the Zulu Commercial Compatibility Kit (CCK). The CCK contains additional functionality that is not included in the OpenJDK source, but which will help ensure compatibility in applications that utilize certain features that Oracle bundles with HotSpot outside the specifications of Java SE. The Zulu CCK is free and can be added easily to Zulu as part of your normal software update process. Currently, the CCK contains Monotype™ Lucida fonts.

Zulu Enterprise subscribers also are entitled to full support for Zulu Flight Recorder and Zulu Mission Control, two powerful tools to help with Java application troubleshooting as well as performance monitoring and management. Download Zulu Mission Control or the Zulu Mission control datasheet.

Is OpenJDK similar to Oracle HotSpot?

OpenJDK is the reference implementation for Java SE. HotSpot is the brand name that Oracle may use for its commercial JDKs and JREs. All development by Oracle and others in the Java Community (Red Hat, IBM, Azul, and others) for Java 7 and later versions was and is done completely in the open as part of the OpenJDK project. The only exception to this open development process is related to security fixes, where development is done in private and source changes are only introduced into the OpenJDK source base on specific scheduled (typically quarterly) timeframes. 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). The fact that OpenJDK and Oracle HotSpot are created from the same underlying source code is exactly why OpenJDK builds and Oracle HotSpot are largely indistinguishable except for some areas that are outside the specifications of Java SE and are further described below.

Does Zulu have any font rendering/font differences compared to Oracle HotSpot?

Possibly. Oracle HotSpot utilizes T2K, a third party closed source font rendering library, in addition to Monotype Lucida font files. OpenJDK depends on the FreeType font rendering library which Zulu also integrates. There are certain rare situations where the rendering between T2K and FreeType can be slightly different. As OpenJDK does not include Lucida fonts, 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 for older releases of Java SE. Current builds of Zulu ship with unlimited cipher strength by default.

Does Zulu use JavaFX?

Java FX is an Oracle product that was released to the OpenJDK project in 2017. OpenJFX is not part of OpenJDK JDK/JRE distributions and is therefore not included in Zulu distributions. Azul does provide commercial support for OpenJFX, and those interested in OpenJFX community builds can download it from the Zulu Community download page.

Does Zulu support Java Mission Control or Flight Recorder commercial features?

Yes, Flight Recorder and Mission Control are part of all Zulu builds of OpenJDK 8 and 11.

In addition, free Community builds of Zulu Mission Control are available for download and use from https://www.azul.com/products/zulu-mission-control/.

Does Zulu include the SNMP Protocol Adapter?

No. The SNMP protocol adapter is not part of the Java SE standard or the OpenJDK project, but Oracle does integrate it as part of HotSpot. It is recommended that Zulu customers use JMX instead, which is part of the Java SE standard. Some customers have chosen to implement SNMP4J, which can be downloaded at snmp4j.org.

Which Color Matching library does Zulu use?

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

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

Oracle JDK 9, OpenJDK 9, and Zulu 8 and 9 include the Marlin open source library. Older Oracle releases (Oracle JDK 8 and prior) ship the third-party Ductus anti-aliasing library. Older OpenJDK releases (JDK 8 and prior) and older Zulu releases (JDK 7 and prior) use the Pisces open source rendering library.

Which JavaScript engine does Zulu use?

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.  

This table summarizes some of the key variations between prior versions of the proprietary Oracle Java SE and Zulu Community and Enterprise builds of OpenJDK that are listed above:

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

Zulu community downloads are always full JDKs, targeting developer-focused use cases and represent the top-of-tree OpenJDK. Zulu Enterprise subscribers have access to JDK and JRE builds, and other tailored builds, targeting both developer and production use cases. Out-of-cycle bug fixes and security updates also appear in builds of Zulu Enterprise prior to their eventually being contributed to OpenJDK.

Useful Basic Definitions:

OpenJDK is the open source project where all new Java versions (Java 7 and beyond) 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.