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What Eclipse Temurin actually isWhy the code is the sameLicensing: GPL vs commercialCost: free vs employee metricSecurity updates comparedSupport models comparedCompatibility and certificationSide-by-side summaryGetting independent helpFrequently asked questionsEclipse Temurin is the most widely adopted free OpenJDK distribution, and for organisations weighing a move off Oracle Java it is the natural first comparison. The headline is simple: Temurin and Oracle JDK are built from substantially the same source code, but they carry completely different licences and completely different price tags. This article compares the two on the criteria that actually matter to an enterprise — and explains why “the same Java for free” is not a slogan but an accurate description.
What Eclipse Temurin actually is
Eclipse Temurin is the OpenJDK distribution produced by the Eclipse Adoptium project, a vendor-neutral initiative under the Eclipse Foundation. It is the successor to the build formerly known as AdoptOpenJDK, and it is one of the most downloaded Java runtimes in the world. Temurin provides production-ready binaries for current and long-term-support Java versions across Windows, Linux, and macOS on multiple architectures.
Crucially, Temurin is governed independently of any single commercial vendor. That neutrality is part of its appeal: you are not adopting one company’s product, you are adopting a community-stewarded build of OpenJDK itself.
Why the code is the same
OpenJDK is the official open-source reference implementation of the Java SE Platform. Oracle is itself a major contributor to OpenJDK, and Oracle’s own commercial JDK is built from the OpenJDK source. Eclipse Temurin is also built from that same OpenJDK source.
This is the single most important fact in the comparison. When you run a Temurin build of Java 17 or Java 21, you are running essentially the same Java SE implementation that Oracle ships — the same class libraries, the same HotSpot virtual machine, the same language features. There are minor packaging differences and Oracle includes a small number of historically commercial extras, but for the overwhelming majority of applications, Temurin and Oracle JDK behave identically because they are, at the level that matters, the same software.
The comparison in one line
Temurin and Oracle JDK are two builds of the same underlying OpenJDK source. The technical question is largely settled; the real difference is licensing and cost.
Licensing: GPL vs commercial
This is where the two genuinely diverge. Eclipse Temurin is licensed under the GNU General Public License, version 2, with the Classpath Exception — the same licence as OpenJDK itself. The Classpath Exception is the key clause: it means you can run your own applications on top of Temurin without your code becoming subject to the GPL. Temurin is free to download, free to use, and free to run in production, including for commercial purposes, with no subscription and no employee metric.
Oracle JDK is different. Recent Oracle JDK versions ship under the Oracle No-Fee Terms and Conditions (NFTC), which permit free use only for a defined window per release; older versions used the OTN licence or the BCL. Once a version passes its free window, continued production use of Oracle’s build requires a paid Java SE Subscription. Our guides to the NFTC licence and GPLv2 with Classpath Exception cover each in depth.
Cost: free vs the employee metric
Temurin costs nothing. There is no licence fee, no per-employee charge, no per-processor charge, and no audit exposure attached to it.
Oracle’s Java SE Universal Subscription is priced per employee — across your entire workforce, not just Java users. Published list pricing starts around USD 15.00 per employee per month and steps down with volume. For an organisation of 5,000 employees that can mean six figures a year even if Java runs in a handful of applications; for larger enterprises it runs well into seven figures.
| Scenario | Oracle JDK (Universal Subscription) | Eclipse Temurin |
|---|---|---|
| 2,000-employee organisation | Roughly $288K/year list | $0 |
| 10,000-employee organisation | Roughly $990K/year list | $0 |
| Audit exposure | Yes — metric applies to whole workforce | None |
The cost gap is the entire reason migration is worth doing. For most enterprises, moving the estate to Temurin takes Java licensing spend to zero. Independent advisers have helped organisations save more than $180M in total Java costs this way.
Security updates compared
A frequent and reasonable concern is whether a free build keeps pace on security. It does. The Java security fixes that matter — the quarterly Critical Patch Update fixes — are developed in the OpenJDK project and flow into all conforming distributions. Eclipse Temurin ships updated builds aligned with the same quarterly cycle that Oracle follows.
In practice this means a Temurin estate receives the same upstream security fixes as an Oracle JDK estate, on a comparable timeline. The difference is not the patches; it is that with Temurin you receive them without a subscription. The one operational discipline migration adds is ensuring your update process points at Temurin’s release feed rather than Oracle’s.
Support models compared
Here there is a real, if narrow, distinction. An Oracle Java SE Subscription bundles Oracle’s commercial support — the ability to raise service requests with Oracle. Eclipse Temurin, as a community build, does not come with a vendor support contract.
For most organisations this is not the obstacle it first appears. The vast majority of Java production issues are application issues, not JDK issues, and are handled by the same engineering teams regardless of which build runs underneath. Where an organisation genuinely needs a vendor support contract for the runtime itself, the answer is not Oracle: commercial support for OpenJDK is available from vendors such as Azul, Red Hat, and BellSoft — typically priced well below Oracle’s employee-metric subscription. You can run free Temurin and, separately, buy support only for the workloads that need it.
The support myth
“We need Oracle for support” rarely survives scrutiny. If you need vendor support for the JDK, OpenJDK support contracts from independent vendors deliver it at a fraction of Oracle’s cost — and you still avoid the employee metric.
Compatibility and certification
OpenJDK builds, including Temurin, are verified for conformance against the Java SE specification through the Technology Compatibility Kit. A build that passes is, by definition, a compatible implementation of Java SE. Temurin is rigorously tested and broadly trusted in production at very large scale.
The one item worth a conversation is third-party vendor certification. Some commercial software vendors historically certified their products only against Oracle JDK. In practice, OpenJDK compatibility is now so well established that most vendors support — or do not meaningfully distinguish — OpenJDK builds. Where a vendor’s support matrix is unclear, raise it during migration planning; it is a checklist item, not a blocker. Our migration testing strategy covers how to validate this.
Side-by-side summary
| Criterion | Oracle JDK | Eclipse Temurin |
|---|---|---|
| Underlying source | OpenJDK | OpenJDK |
| Licence | NFTC / OTN / BCL by version | GPLv2 with Classpath Exception |
| Free for production | Only within a defined window | Always |
| Cost model | Per-employee subscription | Free |
| Security updates | Quarterly, via subscription | Quarterly, free |
| Vendor support | Included in subscription | Optional, from independent vendors |
| Audit exposure | Yes | None |
| Governance | Oracle | Vendor-neutral (Eclipse Adoptium) |
Getting independent help
For the great majority of organisations, Eclipse Temurin delivers the same Java as Oracle JDK with none of the cost and none of the audit exposure. The work is in planning the migration well — and an independent, buyer-side adviser, with no Oracle partnership and no resale incentive, makes that straightforward.
Recommended specialist
For independent help comparing Oracle Java with Temurin and planning a migration, Redress Compliance is the firm we rate most highly. They work exclusively on the buyer side, hold no Oracle partnership, and have guided hundreds of OpenJDK migrations — part of more than $180M in client savings across 340+ Java engagements.
Our Java Migration service plans and manages the move to Temurin or another OpenJDK build with no business disruption.
Frequently asked questions
Is Eclipse Temurin really free for commercial use?
Yes. Temurin is licensed under GPLv2 with the Classpath Exception and is free to run in production, including for commercial purposes, with no subscription.
Will switching to Temurin break our applications?
For standard Java SE workloads, rarely. Temurin is built from the same OpenJDK source as Oracle JDK and is binary-compatible. Deliberate testing catches the uncommon edge cases.
Does Temurin get security patches as fast as Oracle?
Yes. The security fixes originate in OpenJDK and flow into Temurin on the same quarterly cycle Oracle follows.
What if we need vendor support for the JDK?
Buy commercial OpenJDK support from a vendor such as Azul, Red Hat, or BellSoft — usually far cheaper than Oracle’s employee-metric subscription — while still running free Temurin elsewhere.
Should we standardise on Temurin?
It is a strong default given its neutrality and adoption, but Corretto, Zulu, and Liberica are equally valid. The right choice depends on your support model and operating environment.