Alternative Java Options: Exploring OpenJDK Distributions and What Comes After Oracle Java SE

Why Oracle Java Alternatives Are Mainstream in 2026

Until January 2023, many enterprises operated Oracle Java SE under older licensing agreements — the Binary Code Licence (BCL) or the Oracle Technology Network (OTN) licence — which permitted free use for development and certain production scenarios. Oracle's introduction of the Java SE Universal Subscription changed that calculus fundamentally. The new model requires organisations to purchase a subscription for every employee — including contractors, part-time workers, and third-party staff supporting internal business operations — regardless of how many of those employees actually use Java.

For a company with 10,000 employees, the Oracle Java SE Universal Subscription costs approximately $100,000–$180,000 per year depending on the per-employee tier. For a 50,000-employee global enterprise, the cost rises to $400,000–$600,000 annually. Gartner analysis from the period noted that typical Oracle Java customers were paying between two and five times their previous costs, with outliers experiencing increases of ten times or more.

The OpenJDK ecosystem — which existed before Oracle's pricing change and which Oracle itself participates in — offers free, production-ready Java distributions that are technically equivalent to Oracle Java SE. Understanding what these distributions offer and how they differ is essential before making a migration decision.

What Is OpenJDK and Why It Matters

OpenJDK is the open-source reference implementation of the Java Platform, Standard Edition (Java SE). It is maintained through the OpenJDK project at openjdk.java.net and is developed collaboratively by Oracle, Red Hat, IBM, Microsoft, Amazon, Azul, and many other contributors. The key point is that Oracle JDK — the commercially supported product — is built from the same source code as OpenJDK. Since Java 11, the technical differences between Oracle JDK and OpenJDK builds have been minimal to non-existent for most enterprise workloads.

TCK verification (Technology Compatibility Kit) is the quality standard that matters most for enterprise deployments. A TCK-verified OpenJDK distribution has passed Oracle's compatibility test suite and is confirmed to be a fully compatible Java SE implementation. All the distributions reviewed in this article are TCK-verified, which means they are safe choices for production Java workloads.

The Five Major OpenJDK Alternatives to Oracle Java SE

Eclipse Temurin (formerly AdoptOpenJDK)

Eclipse Temurin is the community standard for free, vendor-neutral OpenJDK binaries. It is produced by the Eclipse Foundation's Adoptium project, backed by IBM, Red Hat, Microsoft, and Google. Temurin builds are TCK-verified, available for Linux, Windows, and macOS, and supported across all major LTS versions (Java 8, 11, 17, 21, and beyond). Cost: free. Temurin is the default choice for organisations that want a drop-in replacement for Oracle Java SE without commercial vendor dependency. It does not include commercial support — organisations that require SLA-backed support for production Java should evaluate a supported distribution.

Amazon Corretto

Amazon Corretto is Amazon's production-ready distribution of OpenJDK, used internally by Amazon and offered publicly as free, long-term-supported binaries. Corretto is TCK-verified, available for all major platforms and operating systems, and includes patches for security vulnerabilities and performance improvements that Amazon develops internally. Cost: free for all versions. Corretto is an excellent choice for organisations running workloads on AWS, where Amazon's internal patching cadence and integration with AWS services adds incremental value. It is equally suitable for on-premise and non-AWS cloud deployments.

Microsoft Build of OpenJDK

Microsoft released its own free, long-term-supported OpenJDK distribution in 2021. The Microsoft Build of OpenJDK is TCK-verified, tested against the Eclipse Adoptium quality assurance suite, and available for Windows, Linux, and macOS. Microsoft is a JCP Executive Committee member and a contributor to the Adoptium Working Group, which underlines the credibility of its Java commitment. Cost: free. This distribution is particularly well-suited for organisations running Java workloads on Azure or in Microsoft-centric environments, where Microsoft's support channels are already established.

Azul Zulu / Azul Platform Core

Azul Systems offers two Java products relevant to Oracle Java replacements. Azul Zulu is a free, TCK-verified OpenJDK distribution available for all major platforms, including some platforms not covered by Temurin or Corretto. Azul Platform Core (previously Azul Zulu Enterprise) is a commercially supported version with SLAs, enterprise support, and Azul's proprietary performance optimisations. Cost: Zulu is free; Platform Core is a paid commercial subscription. Azul is positioned explicitly as a drop-in replacement for Oracle Java SE at dramatically lower cost than Oracle's subscription model. Organisations that need commercial-grade support for Java but want to exit Oracle should evaluate Azul Platform Core as a primary alternative.

Red Hat Build of OpenJDK

Red Hat's build of OpenJDK is included with Red Hat Enterprise Linux (RHEL) subscriptions and is available separately with commercial support. Red Hat OpenJDK is TCK-verified, closely aligned with upstream OpenJDK development, and supported through Red Hat's enterprise support infrastructure. Cost: included with RHEL subscriptions; separately available with Red Hat support subscription. For organisations already running a significant RHEL footprint, Red Hat OpenJDK is often the lowest-friction Oracle Java replacement — the binaries are already part of the operating system subscription, and the support infrastructure is already in place.

Choosing the Right Alternative: Decision Framework

The right OpenJDK distribution depends on three primary factors: your cloud and infrastructure environment, your requirement for commercial support, and your operational Java inventory.

If you run primarily on AWS: Amazon Corretto is the natural first choice — free, well-maintained, and integrated with AWS tools and services. If you need commercial support, Azul Platform Core on AWS is an alternative.

If you run primarily on Azure or in a Microsoft environment: Microsoft Build of OpenJDK is the natural first choice — free, supported by Microsoft's quality infrastructure, and well-integrated with Azure DevOps pipelines and tooling.

If you run primarily on RHEL: Red Hat OpenJDK is likely already on your systems as part of your RHEL subscription. Validate that the version coverage meets your needs (Java 8, 11, 17, 21) and use it as the default.

If you require commercial support and SLAs comparable to Oracle's: Azul Platform Core is the most widely deployed commercial Oracle Java SE alternative. It is priced on a per-machine or per-JVM basis — not per employee — which makes it significantly cheaper than Oracle's Universal Subscription for most enterprise deployments.

If you want the most vendor-neutral, community-governed choice: Eclipse Temurin is the standard. It has no single commercial vendor behind it, which reduces dependency risk. For organisations with internal Java expertise who do not require vendor-backed SLAs, Temurin is often the most appropriate choice.

Migration Risks and How to Manage Them

Migrating from Oracle Java SE to an OpenJDK distribution is technically straightforward for the majority of enterprise workloads. The primary risks are not compatibility — TCK verification provides a strong foundation — but rather process and inventory management.

The first risk is incomplete inventory. Many organisations do not have a comprehensive picture of how many Oracle JDK installations they have, which versions are in use, and which applications depend on which Java version. Before migrating, conduct a full Java inventory using a combination of software asset management tools and network-based discovery. You cannot manage a migration you have not scoped.

The second risk is application compatibility with a specific JVM version. If your organisation is running applications on Java 8 — which is still widespread in legacy enterprise environments — migrating to a newer LTS version (Java 11, 17, or 21) as part of the Oracle exit introduces application-level risk beyond the Oracle JDK to OpenJDK switch. Where possible, separate the JVM vendor change (Oracle to OpenJDK) from the JVM version change (8 to 17) — do one, validate, then do the other.

The third risk is Java support for ISV applications. Some independent software vendors specify Oracle Java SE as a supported runtime for their products. Before migrating, check the ISV support matrix for each application in your estate. In practice, most major ISVs have expanded their support matrices to include Eclipse Temurin, Amazon Corretto, and Azul Zulu — but this must be verified for your specific application versions.

What Happens if You Stay on Oracle Java SE

Organisations that decide to remain on Oracle Java SE must understand the full commercial exposure. Oracle's per-employee subscription increases by 8% annually — this is the stated escalation built into the Universal Subscription pricing model. Over a five-year period, an organisation paying $200,000 per year in year one will pay approximately $272,000 in year five — and the same headcount growth that compounds your employee count also compounds your Java subscription cost automatically, since the model prices every employee regardless of actual Java usage.

Oracle is also actively enforcing the new licensing model. Organisations that have not yet moved to the Universal Subscription but continue to run Oracle JDK in production are at material audit risk. Oracle's License Management Services team has been systematically reaching out to organisations with legacy BCL and OTN deployments to convert them to paid subscriptions. An organisation that receives an Oracle Java audit notice while running unlicensed Oracle JDK in production has limited negotiating leverage and significant financial exposure.

If your organisation chooses to remain with Oracle Java SE — perhaps because of ISV requirements, contractual obligations, or operational constraints — the priority is to negotiate the subscription terms rather than accept Oracle's standard pricing. Volume discounts, multi-year commitments, and bundled Oracle subscription deals can reduce the effective per-employee rate. An independent advisor with current Oracle Java deal benchmarks can quantify what is achievable.

Action Plan: Moving Away from Oracle Java SE

The following sequence applies to organisations that have decided to exit Oracle Java SE and migrate to an OpenJDK alternative. It is structured to minimise risk while achieving the cost reduction as quickly as possible.

First, complete a full Java inventory — version, edition, installation location, owning application, and licence type (BCL, OTN, NFTC, or subscription). Use this inventory to calculate your current Oracle exposure and the scope of the migration work.

Second, select your target distribution based on your infrastructure environment and support requirements. For most enterprise organisations, this will be one or two distributions — typically Amazon Corretto or Microsoft Build of OpenJDK for cloud workloads, and Eclipse Temurin or Azul Zulu for on-premise workloads requiring a single standardised JVM.

Third, validate ISV support matrices for all applications dependent on Java. Where ISVs do not explicitly support your chosen OpenJDK distribution, engage the ISV directly — the support position is often broader than the published documentation suggests.

Fourth, pilot the migration with a non-critical workload using the target JVM, run integration tests, and validate that no functional regression is introduced by the JVM change. Document the results and use them to build the business case for the full migration.

Fifth, execute the full migration in waves, starting with development and test environments, then pre-production, then production. Keep Oracle JDK installed during the transition period but do not register new systems. Once migration is complete, remove Oracle JDK from all systems and terminate your Oracle Java subscription.

Summary: The OpenJDK Ecosystem Is Mature and Migration-Ready

The OpenJDK ecosystem is sufficiently mature that for the vast majority of enterprise Java workloads, migration from Oracle Java SE is a practical exercise in inventory management and testing — not a fundamental technology risk. The distributions covered in this article are TCK-verified, actively maintained, and backed by major technology vendors with credible long-term support commitments.

The financial case for migration is compelling: Temurin, Corretto, and the Microsoft Build of OpenJDK are free. Azul Platform Core provides commercial-grade support at a fraction of Oracle's per-employee subscription cost. And the longer you delay migration, the more Oracle's annual 8% subscription escalation increases your exposure.

Start with an accurate Java inventory, select a distribution that matches your infrastructure environment and support requirements, validate ISV compatibility, and execute in waves. The organisations that have already completed this migration consistently report that the operational complexity was lower than anticipated — and the cost saving was exactly as significant as the licensing analysis predicted.