Azul Core is Azul Systems’ commercially supported distribution of OpenJDK. The Azul Software Agreement calls it Azul Platform Core, and the Azul Core page says it was formerly Zulu Enterprise and Zulu Embedded.[3][1] The same Azul Zulu Builds of OpenJDK are also available free of charge. Azul describes them as “Free to download and use”.[2] Two things separate the free product from the paid one. The paid product adds Subscriber Availability builds, security-only updates delivered on an SLA, support, and indemnification. Its licence form also differs. Exhibit A-2 grants “a perpetual, worldwide, nonexclusive right to use the Product”, and what the customer pays for is time-based Support Services.[1] Paid capacity is counted in Units of one Virtual Core, or one Desktop where the Order Form allows desktop use.[1] This page explains how to tell the two apart and how to count Units. For the employee-based alternative many customers are replacing, see Oracle Java SE licensing.
Editions
Azul describes two builds of Zulu. “Azul offers both an unlicensed Community Availability (CA) and, through Azul Core, a licensed Subscriber Availability (SA) version of our Zulu builds of OpenJDK.” Zulu CA requires no licensing fee but has none of the security and compliance features of Zulu SA.[3]
| Edition | What it includes (vendor description) | Terms and price |
|---|---|---|
| Azul Zulu Builds of OpenJDK (CA) | 100% open source; free quarterly updates; Java 8, 11, 17, 21, 25; Windows, Linux, macOS, Solaris; x86, Arm, PPC[2] | Azul builds of OpenJDK Terms of Use; free[4][2] |
| Azul Core, Standard tier | CPUs and PSUs; monthly CSPUs as appropriate; business hours, next-business-day response; limited tickets; CPU SLA maximum 15 days[3] | Per vCore or Desktop, by quote[2] |
| Azul Core, Premium tier | As Standard plus out-of-cycle patches; 24x7x365 with one-hour first response; unlimited tickets; CPU SLA maximum 48 hours[3] | Per vCore or Desktop, by quote[2] |
| Azul Core for OEMs and ISVs | Redistribution-ready runtimes; packaging and pricing model agreed with Azul sales[3] | Distribution Rights in the Order (Exhibit C)[1] |
The pricing page lists what Azul Core adds to the free builds. These include out-of-cycle critical fixes, an SLA for quarterly updates, and “IP Patent and license non-contamination indemnification”. The list also names Legacy Production Support for Java 6 and 7, feature enhancements such as FIPS 140-2, and support for Eclipse Temurin builds.[2] Azul Platform Core consists of Azul Zulu Builds of OpenJDK and Azul Mission Control.[1]
Published prices. The Azul Support for OpenJDK FAQ gives starting prices. Desktops start at $25 per Desktop per year. Server support is priced per physical core or per vCore “for cloud-based deployments”: vCores start at $20 per year and a physical core costs $40 per year, counting as two vCores. All of these fall with volume discounts and support tier. The standard term is one year.[5] Catalog SKUs: Desktop, vCore, physical core, free Zulu CA, Azul Core subscription. Catalog proof: Azul Support for OpenJDK starting prices: $25 per Desktop, $20 per vCore, $40 per physical core per year.
Metrics
| Azul term | Catalog row | Contract definition |
|---|---|---|
| Virtual Core (vCore) | Azul Core Unit (Virtual Core) | A virtual representation of processing power in a single hardware virtualization that can run its own operating system; each maps to one hardware thread; one physical core equals two Virtual Cores where only physical cores can be counted[1] |
| Unit | same row | Software Services with one or more instances of Azul Zulu Builds of OpenJDK on one Virtual Core, and Azul Mission Control on an unlimited number of Virtual Cores[1] |
| Desktop | Azul Core Unit (Desktop) | A physical desktop or laptop computer; for Desktop-only purchases, one Unit per Desktop[1] |
| Supported Instance (2019) | Supported Instance (2019 agreement) | Zulu Enterprise on one Physical Node (up to two sockets) or one Virtual Node (up to 32 virtual cores)[7] |
Counting / floors
Hardware threads, not cores (Rev July-2025). A Virtual Core maps to a single hardware thread. A physical server with simultaneous multithreading therefore has twice as many Virtual Cores as cores. Where the customer can only count physical cores, each counts as two Virtual Cores.[1] The price list reflects the same ratio: $40 per physical core against $20 per vCore.[5] Catalog proof: One Virtual Core equals one hardware thread; one physical core equals two Virtual Cores.
One Unit per Virtual Core, however many JVMs (Rev July-2025). A Unit covers “one or more instances” of Azul Zulu on one Virtual Core. Several JVMs sharing a Virtual Core therefore need one Unit, not one per JVM. Azul Mission Control runs on an unlimited number of Virtual Cores within the Unit.[1] Catalog proof: Azul Mission Control runs on an unlimited number of Virtual Cores within a Unit.
Desktops (Rev July-2025). “Unless so expressly stated on an applicable Order Form, Customer is restricted from deploying the Product on Desktops.” Desktop-only Software Services count one Unit per Desktop, including Mission Control on unlimited Desktops.[1] Server Units and Desktop Units are therefore separate entitlements. Catalog proof: Azul Platform Core may not be deployed on Desktops unless the Order Form says so.
Cap on Units (Rev July-2025). The Product may only be used on the number of Units purchased. Support may not be used for more Units than purchased.[1] The licence is perpetual, and Azul says customers can keep using its OpenJDK builds after support expires.[5] So the Unit cap applies while Software Services are active and governs what support covers. It does not decide whether the binaries may run at all. Catalog proof: Product may only be used on the number of Units purchased; Azul OpenJDK builds may be used after the support subscription expires.
Tier per installation (Rev July-2025). Support purchased at one Support Tier cannot be used for installations whose Software Services were bought at a lower tier.[1] An estate that mixes Standard and Premium Units must track which installations belong to which tier. Catalog proof: Higher-tier support cannot be used for installations bought at a lower tier.
Telling CA from SA builds. Azul’s lifecycle documentation shows a sample java -version output in which the runtime line reads “Zulu21.36+17-CA”. The second line names the distribution.[8] Community Availability builds carry no licence fee.[3] Discovery that records the full build string can therefore separate free installations from subscribed ones. Catalog proof: Zulu CA builds carry no licensing fee; Zulu SA builds come with an Azul Core subscription.
Floors. No minimum quantity is published.
Virtualization & partitioning
The Virtual Core definition is written for virtualized infrastructure. A Virtual Core is a virtual representation of processing power “in a single hardware virtualization that can run its own operating system and execute applications like a physical machine”.[1] Guests are counted by their own virtual cores. The published templates contain no host-based licensing option, no partitioning policy and no rule on moving virtual machines between hosts.
Contracts on the September 2019 paper count differently. One Supported Instance covered a Physical Node, meaning a system of up to two processor sockets with unlimited cores per socket, or a Virtual Node, meaning a virtual machine of up to 32 virtual processing cores. Systems with more sockets needed one Supported Instance per two sockets. Larger virtual machines needed one per 32 virtual cores.[7] Moving such a contract to current paper changes the count. A two-socket host with many cores was one Supported Instance, but under the current terms it is counted per hardware thread. Catalog proof: 2019 agreement: one Supported Instance per two-socket Physical Node or 32-core Virtual Node.
Cloud / BYOL
Azul prices vCores for “cloud-based deployments”.[5] The contract definition of Virtual Core applies to cloud instances as it does to on-premises virtual machines.[1] No bring-your-own-licence rule or authorized-cloud list is published. The one cloud-specific program, Zulu for Azure, was free only for Java applications developed and deployed in Microsoft Azure, Azure Stack or Microsoft SQL Server, and “These binaries may not be used for any other purpose.” Its updates ended on 2021-12-31, although existing binaries may be used in perpetuity.[10] Catalog proof: Zulu for Azure binaries were free only for Azure, Azure Stack and SQL Server use; updates ended 2021-12-31.
Programs
- Support tiers. Under Exhibit A-2, Premium/Platinum customers get CVE fixes within 48 hours and Standard customers within 15 days. These times apply to 64-bit Java 8 onward on ARM64 and x86 under Linux, Windows and macOS. Other platforms get 15 and 30 days.[1] The data sheet states the same 15-day and 48-hour update SLAs.[6] Details are in Azul support tiers and lifecycle. Catalog proof: Security update SLA: 48 hours (Premium/Platinum) or 15 days (Standard) for covered platforms.
- Indemnification. For Platinum/Premium tiers, indemnification extends to the Product’s Third-Party Software. It also covers Azul’s certification that the Accessible APIs impose no licence requirements on code running on them.[1] Catalog proof: Platinum/Premium tiers extend indemnification to third-party software and anti-contamination.
- Legacy Production Support. A paid add-on for Java 6 and 7 and for deprecated technologies, governed by Exhibit D.[1]
- Distribution Rights. Distribution Rights are defined by processor, operating system and Java version in the Order. They allow distribution of the Product only inside a Combination Product. The customer may not use the Product internally except as part of that Combination Product.[1] An ISV that also runs Azul Core in its own production estate needs ordinary Units for that use. Under the 2019 paper, Zulu Embedded was sold “in the Product Configuration as specified in an Order”.[7] Catalog proof: Distribution Rights cover the Product only as part of a Combination Product.
- Commercial Compatibility Kit. The CCK adds Monotype fonts and other components. Its terms limit the Font Software to devices with “a properly licensed copy of the Product” and to Internal Use.[9] Catalog proof: Monotype fonts in the Commercial Compatibility Kit are for Internal Use on licensed installations only.
Contract terms
Free builds. Downloading, installing or using Azul Zulu Builds of OpenJDK binds the user to the Azul builds of OpenJDK Terms of Use. The builds are provided “AS IS”. Azul’s aggregate liability for direct damages is capped at one hundred U.S. dollars. Azul has no support obligation unless a separate written support agreement exists.[4] The terms set no unit limit and no fee. Catalog proof: Free Azul Zulu builds are provided as is, without support, under the Terms of Use.
Subscribed builds after expiry. Termination of the Agreement ends all licences except perpetual ones, and those survive only if the customer has not materially breached it.[1] Azul says customers “can continue to use the Azul OpenJDK products after the expiration of their Azul support subscription”.[5] What stops is access to Subscriber Availability updates, support and indemnity. Catalog proof: Azul Platform Core licence is perpetual; the subscription buys time-based support; On termination all licences end except perpetual ones, absent customer breach.
Redistribution without Distribution Rights. Section 3 bars external distribution unless an Exhibit A or Order authorizes it, even where an open source licence would allow it. It also bars selling any Azul product “without paid and active Software Services for such Azul product”.[1] Catalog proof: No external distribution, public posting or third-party use without authorisation.
Out of scope
This page does not cover Azul Prime, which carries a different licence form (see Azul Prime licensing). Nor does it cover Oracle Java SE subscriptions, the licences of third-party components listed by Azul, or Azul’s migration services. Azul’s pages also differ on Java 6 and 7 dates. The roadmap and documentation give December 2029 under Legacy Production Support,[8] while the older Azul Core vs Free OpenJDK page still says December 2027.[11] See Azul support tiers and lifecycle.