Faced with rising costs and compliance risks of Oracle's Java licensing, enterprises are migrating to free, enterprise-grade alternatives. This guide covers OpenJDK, major distributions, licensing comparison, cost-benefit analysis, and migration best practices — enabling you to run Java on your terms.
OpenJDK (Open Java Development Kit) is the open-source project that forms the basis of Java Standard Edition. Sun Microsystems opened the Java SE implementation via OpenJDK starting in 2006, and today Oracle's own JDK is built from the OpenJDK codebase. This means OpenJDK is functionally equivalent to Oracle's Java — it passes the same Technology Compatibility Kit (TCK) tests that certify a Java implementation.
OpenJDK is released under the GNU General Public License version 2 with the Classpath Exception (GPLv2+CPE). This is a free, open-source licence. The Classpath Exception means you can use OpenJDK in your applications (even proprietary ones) without the viral effects of GPL — it does not require you to open-source your code. There are no fees or usage restrictions.
OpenJDK is an open community project led by Oracle and others, with contributions from Red Hat, IBM, Amazon, Azul, Microsoft, and individuals. Each new Java version (e.g., Java 17, 21, 25) is developed within OpenJDK. This collaborative model means innovation and fixes come from a broad base, not just Oracle.
Since OpenJDK is the reference implementation, applications that run on Oracle JDK will run on OpenJDK with few to no changes. Oracle JDK and OpenJDK for a given version are now almost identical — differing mostly in packaging and branding. This compatibility has encouraged many third parties to create optimised builds.
Several vendors and communities produce builds of OpenJDK, often adding value in terms of easier installation, long-term support (LTS) for older versions, or commercial support options. All are based on OpenJDK and are Java SE standard-compliant — applications should run the same on any of them.
Community-driven, high-quality OpenJDK binaries now under the Eclipse Foundation. Covers Java 8, 11, 17, 21+ for all major platforms. Very widely used as a drop-in replacement for Oracle JDK in enterprises due to quality and open governance.
Amazon's distribution of OpenJDK, completely free in any environment. Extended LTS promises: Java 8 until at least 2030, Java 11 until 2032 — often exceeding Oracle's support timelines. Well-tested on AWS services (Lambda, EC2). If running on AWS, support available through your AWS support plan at no extra Corretto fee.
From Azul Systems, a company focused exclusively on Java. Free binaries available; optional commercial support (Azul Platform Core) at ~70% less than Oracle. Top-tier support with SLAs, backported fixes, and coverage for very old versions (Java 6, 7). Builds for many platforms including embedded systems.
Included with RHEL subscriptions at no additional cost. Red Hat is a primary maintainer for Java 8 and 11 in OpenJDK, ensuring long-term updates. For non-RHEL environments, builds can be used freely (official support requires subscription). Strong choice for Red Hat shops — integrates with existing support channels.
Available in free edition and with commercial support. Known for wide range of packages: full JDK, JRE, and lightweight builds for containers (Liberica "Lite"). Emphasis on embedded use (IoT) and fast security patches — typically within 48 hours for critical fixes to supported customers.
IBM's builds come in two flavours: standard HotSpot JVM and IBM's own OpenJ9 JVM (more memory-efficient for certain workloads). Free and open source. Support available as part of IBM product offerings (especially WebSphere customers).
Microsoft produces OpenJDK builds (starting Java 11) for internal use and Azure services. Free for anyone. Microsoft's involvement further underscores the industry shift away from Oracle JDK.
The following comparison highlights the stark difference between Oracle's proprietary model and the open-source alternatives available:
| Distribution | Licence | Cost | Support Model | LTS Updates |
|---|---|---|---|---|
| Oracle Java SE | Proprietary (paid subscription required for commercial use) | ~$15/employee/month (tiered) | Oracle Premier Support included with subscription | Quarterly; only while subscription active |
| Eclipse Temurin | GPLv2+CPE (free) | $0 | Community; third-party commercial available | Quarterly; community-maintained 4+ years |
| Amazon Corretto | GPLv2+CPE (free) | $0 | Amazon (via AWS support plan); community | Quarterly (same-day as Oracle); extended LTS |
| Azul Zulu | GPLv2+CPE (free binaries) | $0 free; optional support ~70% less than Oracle | Optional 24/7 commercial SLAs with Azul | Quarterly; legacy versions maintained for paying customers |
| Red Hat OpenJDK | GPLv2+CPE (free) | $0 (included in RHEL subscription) | Via RHEL support channels; separate subscriptions for Windows | Quarterly; aligned with RHEL lifecycle |
| BellSoft Liberica | GPLv2+CPE (free) | $0 free; optional per-server support | Commercial subscriptions available | Quarterly; 48-hour critical patches for supported customers |
| IBM Semeru | GPLv2+CPE (free) | $0 | Via IBM product agreements | Aligned with IBM product lifecycle |
| Microsoft OpenJDK | GPLv2+CPE (free) | $0 | Microsoft + community | Maintained for current versions |
Facing an Oracle Java audit or considering migration? Get expert guidance on your options — before Oracle sets the agenda.
Java Advisory Services →Migrating from Oracle's Java to an alternative requires effort, but the benefits can be substantial across cost, compliance, support, and strategic flexibility.
The most immediate benefit. Oracle's Java SE Universal Subscription can be very expensive: a company with 5,000 employees would face an annual list cost of roughly $630,000 for Oracle Java. In contrast, using an OpenJDK distribution incurs no licensing costs. Even purchasing a commercial support package (Azul or Red Hat) for critical servers might cost $100,000–$200,000 — a fraction of Oracle's fee. Customers switching from Oracle typically save about 70% in Java licensing and support costs. Over a few years, this is millions of dollars saved for a large enterprise.
By migrating, you essentially remove Oracle's leverage. If you have no Oracle JDK in use, Oracle cannot claim you owe Java licensing fees. This doesn't just save money — it provides peace of mind and avoids the resource drain of compliance audits. Java becomes like any open-source component, with no vendor aggressively auditing for revenue.
One concern is whether switching means slower patches. In practice, this has not been an issue: 84% of organisations that migrated found maintaining security updates as easy or easier than before. OpenJDK updates arrive on a similar schedule as Oracle's (often the same day). Vendors like Amazon and Azul ensure zero-day vulnerabilities are patched promptly. Additionally, since you're not tied to Oracle, you have freedom to upgrade at your own schedule without licence implications.
There's essentially no performance penalty. Oracle JDK and OpenJDK are aligned. Some distributions offer enhancements: Azul's Zing JVM improves garbage collection; OpenJ9 from IBM can be more memory-efficient. Oracle's "commercial features" from Java 8 (Flight Recorder, Mission Control) were open-sourced and available in OpenJDK by Java 11. Feature parity is effectively complete.
Company A: 1,000 employees, 100 Java applications, 200 servers
Oracle cost: ~$12/employee/month × 1,000 = $144,000/year ($432K over 3 years)
Migration to Corretto: $0 licensing. Azul support for 50 critical servers at $500/server/year = $25,000/year ($75K over 3 years)
3-year savings: $357,000 — an 83% reduction, plus zero compliance worries
Even factoring in internal migration labour (tens of thousands), the ROI is extremely high.
If you decide to move to an alternative Java platform, here are the key considerations for ensuring a smooth transition:
Inventory your Java applications and categorise by complexity and criticality. Focus first on straightforward cases (e.g., standard app servers like Tomcat with no unusual Java dependencies). Mission-critical systems should be scheduled for maintenance windows with thorough testing. Develop a migration plan spanning weeks or months for large environments.
Even though OpenJDK builds are drop-in replacements, conduct regression testing for each application. Set up a staging environment with Eclipse Temurin or Amazon Corretto and run the full test suite. Pay attention to logging and garbage collection behaviour (usually minimal differences). If an issue arises, it's typically a misconfiguration that can be fixed with minor tweaks.
For critical systems, run old and new JDKs in parallel in a test environment and compare performance metrics. This alleviates management concerns about performance regression. In many cases you'll see equal performance; in some, even improvements.
If CI/CD pipelines explicitly fetch Oracle JDK or Dockerfiles reference Oracle base images, update to OpenJDK sources. Use official Eclipse Temurin Docker images. Ensure CI servers compile with OpenJDK. Standardise to avoid Oracle JDK sneaking back in via developer machines.
Brief DevOps and support teams about the new JDK. Ensure the team knows that future Java installations must use the approved OpenJDK distribution. Incorporate the alternative JDK into standard build images and documentation. This avoids accidentally reintroducing Oracle JDK later and causing a compliance issue.
Keep monitoring performance, memory usage, and application metrics after switching. It's uncommon to see issues, but due diligence is wise. Community forums or vendor support can help if a real issue surfaces.
Ensure all Oracle JDK binaries are removed from systems or no longer in use. Keep evidence of removal (change management records). Update your software asset repository to mark Oracle Java as "retired." This protects you if Oracle later claims Oracle JDK was found on a machine.
If you had an Oracle Java subscription and are not renewing, formally notify Oracle. Inform procurement and accounts payable to prevent accidental auto-renewals. If within a ULA or other Oracle agreement that includes Java, note that you are now using alternative JDKs.
Enforce the new standard: consider blocking downloads from Oracle's Java download page at the firewall. Provide internal repositories for sanctioned OpenJDK builds. Make the alternative easy to access and Oracle JDK harder to access — ensuring long-term compliance.
If you're considering a move away from Oracle Java, here's how to get started:
Conduct a comprehensive audit to identify where Java is used across your organisation. Note versions and which distribution is in use (Oracle vs. others). This baseline guides migration scope and priorities. Our Java Compliance Assessment can help.
Evaluate options (Corretto, Temurin, Azul, Red Hat, etc.) and choose one or a combination. Many start with a free community option like Temurin or Corretto. If you anticipate needing vendor support, engage Azul, Red Hat, or BellSoft early to understand offerings.
Pick a non-critical application and switch it to the chosen OpenJDK distribution. Observe the process and any issues. This pilot serves as proof of concept and refinement of your migration runbook for broader rollout.
Work with Finance to quantify the cost difference: Oracle costs over 3–5 years vs. alternatives (including any support contracts and one-time migration effort). A clear dollar figure helps get executive buy-in. Often the savings are so significant the project is a financial no-brainer.
Inform application owners and business units. Emphasise this is a behind-the-scenes technical change that should not affect functionality but greatly reduces cost and risk. Getting their support means they'll allocate time for testing.
Create a timeline for migrating batches of applications. Coordinate with maintenance windows. Keep momentum — many companies migrated the bulk of their systems within a few months once they made it a priority.
Update architectural standards to use your chosen JDK for all Java needs. New projects must not download Oracle JDK. Communicate clearly to development teams and IT operations.
Closely monitor Java applications through the first quarterly update cycle. Ensure patches are applied promptly — set up feeds or alerts for your OpenJDK vendor's updates. Share knowledge across teams.
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