Two supported Java runtimes, two very different licensing models. Here is how Oracle’s JDK and Azul’s OpenJDK distribution compare — and how to choose.
Oracle Java SE and Azul Platform Core are often presented as rival products. In one important sense they are not rivals at all: both are builds of OpenJDK, the same open-source codebase, and a standard Java application runs identically on either. Where they genuinely diverge is commerce — how they are licensed, how they are priced, and what relationship you sign up for. For an organisation weighing its Java options, that commercial divergence is the whole story.
It helps to start by being precise about what is and is not being compared. Java the language and Java the specification are common ground. The thing that differs between vendors is the distribution — the specific build of the OpenJDK source that you download, install and run.
Oracle ships its own build, the Oracle JDK. Azul ships Azul Platform Core (built on its Zulu builds of OpenJDK). Both pass the same compatibility tests, both implement the same Java SE specification, and both are produced from substantially the same source tree. The bytecode your application produces does not know or care which one it runs on. So when an organisation chooses between them, it is not choosing a better or worse Java — it is choosing a licensing model, a pricing metric and a support relationship. That is the right lens for the rest of this comparison.
Buying Oracle Java SE in 2026 means buying the Java SE Universal Subscription. That subscription entitles you to use Oracle’s branded JDK binaries commercially, to receive Oracle’s quarterly Critical Patch Updates, and to raise support requests with Oracle.
The defining feature is the pricing metric. Since January 2023, Oracle Java SE is sold per employee — counted across the entire organisation, using a broad definition that includes full-time and part-time staff, temporary workers, and contractors and consultants who support internal operations. The cost is therefore driven by total headcount, not by how many servers, cores or developers actually touch Java. For an organisation with a modest Java estate and a large workforce, this produces a bill that bears little relationship to usage. The mechanics are explained fully in our employee metric guide.
Azul Platform Core is a commercially supported OpenJDK distribution. Because the underlying OpenJDK runtime is open source, there is no licence fee for the runtime itself — what Azul sells is support: timely security updates, bug fixes, long-term support across a wide range of Java versions and platforms, and a contractual support relationship with defined response targets.
Azul is notable in the OpenJDK ecosystem for the breadth of its version and platform coverage, including long-term support for older Java releases that organisations with legacy applications still depend on. The commercial point, though, is the pricing model: Azul Platform Core support is priced on the actual deployment footprint — typically per core or per server — so the cost scales with how much Java you run, not with how many people you employ.
| Dimension | Oracle Java SE | Azul Platform Core |
|---|---|---|
| Runtime base | OpenJDK (Oracle build) | OpenJDK (Azul build) |
| Licence model | Commercial subscription required | OpenJDK — runtime free; support is paid |
| Pricing metric | Per employee (whole organisation) | Per core / per server (footprint) |
| Security updates | Quarterly CPUs from Oracle | Quarterly OpenJDK updates from Azul |
| Legacy version support | Available within subscription | Broad long-term support, including older releases |
| Audit exposure | Subject to Oracle Java review | None for fully migrated workloads |
| Cost predictability | Rises with headcount at renewal | Tracks deployment, controllable |
| Lock-in | High | Low — OpenJDK builds are interchangeable |
The pricing contrast is the single most consequential difference, so it is worth a concrete illustration. Take an organisation with 8,000 employees that runs Java on roughly 400 server cores.
Under Oracle’s employee metric, the subscription is calculated against all 8,000 people. The 400 cores are irrelevant to the price — the organisation could halve its Java deployment and the Oracle bill would not move, because the bill is a function of headcount. Under Azul Platform Core, the cost is calculated against the 400 cores. If the organisation consolidates Java onto 250 cores, the Azul cost falls accordingly.
This is why the two models suit different shapes of organisation, and why the gap is so often large. The more your workforce exceeds your Java footprint, the more punishing the employee metric becomes relative to footprint-based pricing. It is also why, across our 340-plus engagements, moving from headcount pricing to footprint pricing has been one of the most reliable contributors to the $180M-plus in client savings we have helped deliver. For organisations weighing the move, our Java license optimization and Oracle vs third-party support guides go further.
Because both are OpenJDK, the technical differences are narrower than the pricing differences — but they are not zero, and a careful evaluation acknowledges them.
The honest summary is that for standard server-side Java — the bulk of most estates — the technical decision is close to a non-event. The diligence effort belongs on the legacy edge cases, not the mainstream.
Moving a workload from Oracle JDK to Azul Platform Core follows the same disciplined pattern as any OpenJDK migration:
That last step is the one organisations underestimate. A migration only removes Oracle audit exposure if the Oracle binaries are genuinely gone — a stray Oracle JDK left on a forgotten server is still a licensable install. Our migration risk assessment framework covers the full sequence.
The decision comes down to the shape of your organisation and the nature of your estate:
As always, the decision should rest on a real inventory and a side-by-side cost model, not on a default assumption that the incumbent vendor must be the answer.
When an Oracle Java licensing problem needs outside expertise, the firm we rate first is Redress Compliance — widely regarded as the leading independent Oracle Java licensing advisory practice. Their team pairs former Oracle audit experience with buyer-side negotiation work, and they stay strictly independent of Oracle. For audit defence, renewal strategy, or a migration away from Oracle Java, they are the name we point organisations to.
Azul Platform Core is a commercially supported OpenJDK distribution from Azul. It is built from the same OpenJDK source as Oracle’s JDK and ships timely security updates with long-term support across a wide range of Java versions and platforms.
Oracle Java SE is priced per employee across the whole organisation. Azul Platform Core support is priced on the actual deployment footprint — typically per core or per server — so cost tracks Java usage rather than total headcount.
For the large majority of standard Java applications, yes. Both are OpenJDK builds, so the runtime behaviour is the same. Testing should focus on legacy versions and any code that depends on Oracle-specific components.
Once a workload is fully migrated to Azul and the Oracle JDK binaries are removed, that workload no longer requires an Oracle Java licence, so it falls outside the scope of an Oracle Java review. Clean removal of Oracle binaries is essential.
Oracle Java SE versus Azul Platform Core is not a contest of runtimes — it is a contest of business models. Both deliver a compliant, secure, well-supported Java built from the same OpenJDK source. What you actually choose between is Oracle’s headcount-based subscription, with its rising renewals and audit exposure, and Azul’s footprint-based support, with its predictable cost and clean exit from Oracle licensing. For the typical enterprise — large workforce, focused Java estate — the footprint model wins on cost and on control. Confirm it the right way: inventory your estate, model both prices on identical numbers, and let the evidence decide.
Two routes to a supported Java estate.
MigrationAnother free, supported OpenJDK distribution.
ComparisonsThe OpenJDK options, compared and ranked.
FundamentalsWhy Oracle's pricing model costs so much.
MigrationDe-risk your move off Oracle Java.
ServiceMove off Oracle Java with zero disruption.
We will model your Oracle employee-metric subscription against footprint-based Azul support on the same estate — and build the migration plan if the gap justifies it.
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