What Eclipse Temurin is
Eclipse Temurin is the OpenJDK distribution produced by the Eclipse Adoptium project, the successor to the widely used AdoptOpenJDK. It is a fully built, ready to run Java SE runtime assembled from the OpenJDK source, the same source from which Oracle builds its own JDK. The defining characteristic is governance: Temurin sits under the vendor neutral Eclipse Foundation rather than a single commercial vendor, which means no one company controls its licence terms or can convert it into a paid product.
That governance is the reason Temurin has become the default landing place for organisations leaving Oracle Java. When the licensing risk you are escaping is single vendor pricing power, moving to another single vendor only relocates the risk; moving to a foundation governed distribution removes it. This article sits beneath the Oracle Java licensing pillar, and complements the broader build comparison in the OpenJDK versus Oracle JDK guide.
The licensing difference that matters
The entire commercial case turns on licence. Temurin is distributed under the GPLv2 with Classpath Exception, the same open source licence that covers OpenJDK itself, and is free for any use including commercial production, with no per employee subscription, no processor fee, and no usage reporting. Oracle JDK, by contrast, is free only within the No Fee Terms and Conditions window for recent versions, after which production use requires the Java SE Universal Subscription priced against your total workforce.
| Dimension | Eclipse Temurin | Oracle JDK |
|---|---|---|
| Licence | GPLv2 with Classpath Exception | NFTC then OTN / subscription |
| Production cost | Free | Per employee subscription |
| Governance | Eclipse Foundation | Oracle Corporation |
| Support | Optional, third party | Bundled in subscription |
| Usage reporting | None | Employee count required |
The practical consequence is that the cost of running Temurin is the cost of operating it, while the cost of running Oracle JDK in production is a function of how many people the organisation employs. For an enterprise, that difference is frequently the gap between zero licensing spend and a six or seven figure annual subscription, as worked through in the employee metric guide.
Compatibility and TCK certification
The reasonable worry about any Oracle JDK alternative is whether applications will behave identically, and for Temurin the answer is backed by formal certification. Temurin builds pass the Java SE Technology Compatibility Kit, the same conformance suite used to verify any compliant Java implementation, which means a Temurin runtime is a verified Java SE platform rather than an approximate clone. Application bytecode compiled for a given Java version runs the same on Temurin as on Oracle JDK.
The runtime your application sees is the same. What changes is the licence stamped on it and the company that controls that licence.
The few genuine differences lie outside the standard runtime: a small set of Oracle specific commercial features and tools that were historically bundled with Oracle JDK, most of which have either been contributed to OpenJDK or have open equivalents. For the overwhelming majority of server side and application workloads, there is no functional difference to detect, which is why migrations are dominated by inventory and packaging rather than by code remediation.
Support, patching, and release cadence
Temurin tracks the OpenJDK release cadence, shipping the same feature releases and quarterly security updates, including continued updates for long term support versions after Oracle's free window for those versions has closed. This last point is decisive: an organisation on Temurin keeps receiving security patches for an LTS version without the Oracle subscription that Oracle would otherwise require once its NFTC window expires.
On support, Temurin separates the runtime from the service. The builds are free, and enterprise support contracts are available from members of the Adoptium working group and other vendors for organisations that want a contractual SLA and someone to call. This unbundling is the structural advantage over Oracle, where support is fused into a workforce sized subscription; with Temurin you pay for support only if you want it, and only for the estate you actually run, an option also available with Azul Zulu and Amazon Corretto.
Should I use Temurin or Oracle Java?
For most organisations the answer is Temurin, because it delivers the same certified runtime at no licensing cost and under neutral governance. The cases where Oracle JDK is genuinely required are narrow: a hard dependency on an Oracle specific commercial feature with no open equivalent, a vendor application that is only certified against Oracle JDK, or a contractual obligation that names Oracle's distribution. Those cases exist, but they are the exception rather than the rule.
The disciplined approach is to treat Oracle JDK as the special case requiring justification, and a free certified distribution as the default. Where Temurin, Corretto, and Zulu all qualify, the choice between them comes down to operational fit, container base images, cloud integration, and support relationships, rather than to licence, since all three are free. Organisations on Azure should also weigh the Microsoft Build of OpenJDK, whose support is included with the platform. The framework for making that call sits in the Java advisory service.
Migrating from Oracle JDK to Temurin
Because Temurin is a certified Java SE implementation built from the same source, migration is an operational exercise rather than a development project. The work is to inventory where Oracle JDK runs, validate that each application's dependencies have no Oracle specific requirement, repackage deployments and container images to use Temurin, and test through the normal release pipeline. For typical Java estates this is measured in weeks of operational effort, not months of rewriting.
The savings, by contrast, are immediate and recurring, since the Oracle subscription disappears entirely once Oracle branded builds are removed from production. The full sequence, including how to handle the inventory and validation steps and how a migration plan strengthens any open Oracle conversation, is set out in the migrating off Oracle Java guide.
The buyer side view
The practical takeaway is that Eclipse Temurin is the low risk default for organisations that want to stop paying Oracle for Java. It is the same certified runtime, governed by a neutral foundation, free for commercial production, with optional support available separately at a fraction of the Oracle subscription. The compatibility worry that holds buyers back does not survive contact with the TCK certification; the runtime your applications see is the same.
Treat Oracle JDK as the case that needs a specific justification and a free certified distribution as the standard, and the Java licensing problem largely dissolves. Start with the OpenJDK versus Oracle JDK guide for the underlying distinction, the migration guide for the move, and the Java advisory service to choose and standardise a distribution across the estate.
Eclipse Temurin vs Oracle Java: frequently asked questions
Is Eclipse Temurin free for commercial use?
Yes. Temurin is distributed under GPLv2 with Classpath Exception and is free for commercial production with no per employee subscription. It is governed by the vendor neutral Eclipse Foundation, removing the single vendor risk that attaches to Oracle JDK.
Is Temurin the same as Oracle JDK?
Temurin is built from the same OpenJDK source Oracle uses and is TCK certified, so it is a verified, compatible Java SE implementation. Bytecode runs identically on both; the differences are branding, licence, and support, not core runtime behaviour.
Does Temurin offer commercial support?
The builds are free; commercial support is available separately from Adoptium working group members and other vendors, typically at a fraction of the workforce sized Oracle Java subscription.