What the Microsoft Build of OpenJDK is
The Microsoft Build of OpenJDK is a free, production ready OpenJDK distribution that Microsoft assembles, ships, and supports. Microsoft created it because it is itself one of the largest Java users in the world, running Java across Azure services, LinkedIn, Minecraft, and internal systems, and it had a direct commercial interest in a free, well maintained build it controlled rather than paying Oracle's per employee subscription across that footprint. The build it produced is offered to everyone under an open licence.
For buyers, the significance is that a major platform vendor has put its weight behind a free OpenJDK distribution, complete with long term support versions and security updates. That backing addresses the durability concern that sometimes attaches to community builds: this is a distribution maintained by a company with both the resources and the self interest to keep it current. It sits alongside Eclipse Temurin and Amazon Corretto as a credible Oracle alternative, all analysed against Oracle in the Oracle Java licensing pillar.
The licensing and cost contrast
The Microsoft build is distributed under the GPLv2 with Classpath Exception licence, the same open source licence as OpenJDK itself, and is free for all uses including commercial production. There is no per employee subscription, no processor metric, and no obligation to report usage. Oracle JDK, by contrast, is free only within the No Fee Terms and Conditions window for recent versions and then requires the Java SE Universal Subscription for continued production use and patching.
| Dimension | Microsoft Build of OpenJDK | Oracle JDK |
|---|---|---|
| Licence | GPLv2 with Classpath Exception | NFTC then subscription |
| Production cost | Free | Per employee subscription |
| Azure support | Included, no extra cost | Separate Oracle subscription |
| Usage reporting | None | Employee count required |
| Vendor | Microsoft | Oracle |
The cost contrast is the same one that drives every OpenJDK migration: a free build that costs only what it costs to run, versus an Oracle build whose production cost scales with the size of your workforce under the employee metric. For an enterprise, that difference routinely turns a recurring six or seven figure Oracle subscription into zero Java licensing spend, a comparison developed in the OpenJDK versus Oracle JDK guide.
Azure integration and included support
Where the Microsoft build is most compelling is for organisations already on Azure. Microsoft supports the build for Azure customers running supported configurations at no additional cost, folding Java support into the platform relationship rather than charging for it separately. For a business running Java workloads on Azure App Service, Azure Kubernetes Service, or virtual machines, that means a supported, patched Java runtime with no separate Oracle line item at all.
Microsoft turned Java support into a feature of the platform. Oracle turned it into a tax on the workforce.
This bundling is the structural opposite of Oracle's model. Oracle prices Java support as a workforce sized subscription independent of where Java runs; Microsoft treats it as part of the Azure value proposition. For organisations weighing cloud Java costs, this is a material factor, and it interacts with the broader cloud licensing picture covered in the Java licensing in the cloud guide.
Compatibility with Oracle JDK
The Microsoft build is built from the OpenJDK source and is a compatible Java SE implementation, so applications behave the same as on Oracle JDK. Bytecode compiled for a given Java version runs identically, the standard libraries are the same, and the operational tooling is familiar. As with other OpenJDK distributions, the only genuine differences sit outside the standard runtime, in a small set of Oracle specific commercial features that most organisations do not depend on.
This compatibility is what makes the Microsoft build a true replacement rather than a partial one. Teams do not rewrite applications to move to it; they re inventory, repackage, and validate, the same low risk operational pattern that applies to Eclipse Temurin and Amazon Corretto. The runtime your application sees does not change in any way it can detect.
Should I use the Microsoft build or Oracle Java?
For organisations on Azure, the Microsoft build is often the natural default, because it is free, certified, and supported as part of the platform with no separate Oracle cost. For organisations off Azure, it remains a perfectly valid free choice, competing on operational fit with Temurin and Corretto rather than on licence, since all three are free and certified. Oracle JDK earns its place only where a specific Oracle commercial feature, vendor certification, or contractual term genuinely requires it.
The selection logic is the same across all the free distributions: treat Oracle JDK as the exception that must be justified, then choose among the free builds on support relationships, cloud integration, and container base images. Where Azure is the platform, the included support tips the balance toward the Microsoft build; elsewhere the decision is finer, and the framework for making it sits in the Java advisory service.
Using the Microsoft build beyond Azure
A common misconception is that the Microsoft build is locked to Azure. It is not. The binaries are openly published and free to download and run anywhere, on premises, on AWS or Google Cloud, or on developer laptops, and the open source licence imposes no platform restriction. What is specific to Azure is the included support relationship, not the right to use the build.
This means an organisation with a hybrid or multi cloud estate can standardise on the Microsoft build everywhere if it chooses, obtaining included support for its Azure footprint and running the same build, unsupported or supported through another arrangement, elsewhere. For organisations whose goal is a single standard Java distribution across a mixed estate, that flexibility is useful, and it removes Oracle JDK from the picture entirely, which is the objective of the migration guide.
The buyer side view
The practical takeaway is that the Microsoft Build of OpenJDK is a free, certified, well backed Oracle JDK replacement that is especially compelling on Azure, where support comes included, and entirely usable everywhere else. It eliminates the Oracle Java subscription the same way every OpenJDK distribution does, with the added advantage that a major platform vendor maintains it and folds support into the Azure relationship rather than charging a workforce sized fee.
If Azure is already your platform, the Microsoft build is close to a default; if it is not, it joins Temurin and Corretto as a free, low risk standard. Treat Oracle JDK as the case that needs justification, and the licensing cost disappears. Start with the OpenJDK versus Oracle JDK guide for the distinction, the cloud licensing guide for the platform angle, and the Java advisory service to standardise across the estate.
Microsoft Build of OpenJDK vs Oracle Java: frequently asked questions
Is the Microsoft Build of OpenJDK free?
Yes. It is distributed under GPLv2 with Classpath Exception and is free for any use including commercial production, with no per employee subscription. Microsoft provides support at no additional cost for supported Azure configurations, unlike the Oracle JDK subscription.
Can I use the Microsoft Build of OpenJDK outside Azure?
Yes. The binaries are openly available and free to run anywhere, on premises, on other clouds, or on developer machines. The licence does not restrict use to Azure, so it is a valid free alternative regardless of where the workload runs.
Is the Microsoft build a true replacement for Oracle JDK?
For most workloads, yes. It is built from OpenJDK and is a compatible Java SE implementation, so bytecode runs the same. The differences are licence and support, not the core runtime, making migration an operational task like moving to Eclipse Temurin.