What Amazon Corretto is
Amazon Corretto is a no cost, multiplatform, production ready distribution of OpenJDK that Amazon builds, certifies, and supports. It exists because AWS runs Java at enormous scale internally and needed a dependable, freely redistributable JDK; making it public turned an internal asset into a market alternative to Oracle's commercial builds. Corretto is available for Java 8, 11, 17, 21, and current releases, and it carries long term support with regular quarterly security updates. This article sits beneath the Oracle Java licensing pillar and extends the general OpenJDK versus Oracle JDK comparison.
The crucial point for licensing is that Corretto is OpenJDK under the GPL with the Classpath Exception, the same open source license that governs the reference implementation. It is not Oracle's commercially licensed JDK, so using it creates no Java SE Universal Subscription obligation. You can deploy it on any number of servers, in any cloud, for any workforce size, at no license cost.
Compatibility and the source question
The reasonable worry when leaving Oracle Java is whether applications will behave differently on another build. For Corretto the answer is reassuring, because Corretto is built from the OpenJDK source that Oracle JDK is also built from. The two share the same class libraries, the same language behaviour, and pass the same Java compatibility tests. For ordinary enterprise applications the runtime is interchangeable, and most migrations are a matter of swapping the binary and retesting rather than rewriting code.
Corretto and Oracle JDK are built from the same source. What you pay Oracle for is the brand and the support contract, not a different Java.
Differences that do exist are at the margins: specific bundled tools, certain garbage collector defaults, and a small number of commercial features that Oracle historically gated. The deeper treatment of those edge cases is in the OpenJDK versus Oracle JDK guide, and they rarely affect a typical migration. The general approach is set out in the migrating off Oracle Java guide.
The cost comparison
The financial contrast is the entire point. Oracle Java is licensed through the employee subscription, which multiplies a per employee rate across your total workforce, including contractors, regardless of how much Java you run, and even its free option, the No Fee Terms and Conditions, expires per version. Corretto is free. For an organisation of any meaningful size, the difference is not incremental, it is the elimination of a recurring six or seven figure cost.
| Dimension | Amazon Corretto | Oracle Java |
|---|---|---|
| License cost | Free | Employee subscription |
| Pricing basis | None | Total workforce |
| Security updates | Quarterly, long term | Quarterly, with subscription |
| Source base | OpenJDK | OpenJDK |
| Commercial support | Via AWS, optional paid | Included in subscription |
| Cloud lock in | None, runs anywhere | None |
To quantify the saving for your own organisation, establish your true subscription cost using the employee metric guide and the Java pricing guide, then set it against the zero license cost of Corretto.
Support and patching without Oracle
The objection that switching means losing support does not survive scrutiny. Corretto receives security patches and bug fixes on a quarterly cadence aligned with the OpenJDK update releases, and AWS commits to long term support for its LTS versions well beyond the dates Oracle offers free updates for its own builds. For workloads running on AWS, the support is effectively part of the platform; for workloads elsewhere, Corretto can still be used freely and patched from Amazon's public builds.
Where an organisation genuinely needs a contractual support relationship with service level commitments, that can be obtained without returning to Oracle, either through AWS support tiers or through a third party Java support vendor. The point is that support and the Oracle subscription are separable; you do not have to buy Oracle's license to get supported Java. Corretto is not the only such option, and the Azul Zulu comparison covers an alternative with formal paid support tiers.
Is Amazon Corretto really free for production?
Yes. Amazon Corretto is free for production use, with no license fee, no usage reporting, and no employee based metric. It is distributed under the OpenJDK open source license, and Amazon provides the security updates at no charge. There is no Oracle subscription obligation created by running it, in the cloud or on premises.
The only cost is the operational one of any platform change: testing your applications on the new runtime and updating your build and deployment pipelines to pull Corretto instead of Oracle JDK. For most enterprises that is a modest, one time project measured against a permanent removal of the Oracle subscription. The route is described in the migration guide and the cloud specifics in the Java in the cloud guide.
Why Amazon built and gave away Corretto
Corretto exists for a reason that reassures buyers about its durability. Amazon runs an enormous number of Java services internally, and when Oracle changed its licensing terms, Amazon needed a JDK it could depend on without commercial uncertainty or per employee fees. Rather than build a private fork, it productised its internal distribution and released it publicly, which means Corretto is the same Java that one of the largest Java operators on earth trusts for its own production systems.
This origin story addresses the most common objection to free Java, that something given away cannot be serious. Corretto is not a community side project maintained in spare time; it is an engineered, certified distribution backed by a company with a direct operational stake in its quality. Amazon fixes bugs and ships security patches because it runs the result itself, which aligns its incentives with the users who adopt it.
For a buyer weighing whether to leave Oracle, that alignment is the point. The question is not whether free Java can be trusted in the abstract but whether this specific distribution is dependable, and Corretto's pedigree answers it. The broader comparison of open builds against Oracle's own is in the OpenJDK versus Oracle JDK guide, and the practical switch is covered in the migration guide.
Migrating from Oracle JDK to Corretto
The mechanics of moving from Oracle JDK to Corretto are simpler than most teams expect, because the two are built from the same source. The starting point is an inventory that identifies every Oracle JDK in the estate by build string, since the goal is to replace only the licensable Oracle binaries and leave any existing free builds in place. With that map in hand, the work is largely a matter of installing Corretto, repointing the relevant environment variables and runtime configuration, and retesting the applications.
Most enterprise applications run unchanged, because they depend on standard Java behaviour that Corretto reproduces faithfully. The areas that warrant attention are the margins: any reliance on tools that Oracle bundled but the open builds do not, any tuning that assumed a particular garbage collector default, and any startup scripts that hard code an Oracle path. These are usually quick to identify and adjust, and they rarely block a migration.
The remaining task is operational rather than technical: updating build pipelines, container base images, and provisioning automation to pull Corretto by default, so that the organisation does not silently reintroduce Oracle JDK over time. Standardising the supply chain on the free build is what makes the saving permanent rather than temporary, and it is a step our Java advisory service treats as part of the migration rather than an afterthought.
When staying with Oracle Java still makes sense
Intellectual honesty requires acknowledging the narrow cases where Oracle Java remains the rational choice. The clearest is a hard dependency on a feature that exists only in Oracle's commercial builds and has no equivalent in the open distributions, where re engineering around it would cost more than the subscription. In modern Java versions these exclusive features are few, because Oracle has contributed most of them to OpenJDK, but a legacy application built against one can create genuine lock in.
A second case is a contractual or regulatory requirement that mandates a specific vendor support relationship which, for organisational reasons, must be Oracle. This is rare, because comparable support is available from Amazon, Azul, and others, but where an existing enterprise agreement bundles Java support on favourable terms, the marginal cost of Oracle Java may be effectively zero and switching would save nothing.
Outside these narrow situations, the case for paying Oracle's employee subscription is hard to sustain once a free, supported, source compatible alternative exists. For the overwhelming majority of organisations, Corretto or a comparable build removes the premise of the bill, which is why the default recommendation is to evaluate the switch seriously rather than to renew by habit. Compare the alternatives in the Azul Zulu guide and quantify the stakes with the Java licensing white paper.
Performance and feature parity in practice
A reasonable technical question when leaving Oracle JDK is whether performance or behaviour will regress, and the evidence from large scale adopters is reassuring. Because Corretto is built from the same OpenJDK source, it shares the same compilers, garbage collectors, and runtime behaviour, so for the overwhelming majority of workloads performance is indistinguishable. Amazon runs its own production estate on Corretto, which is a strong practical signal that the distribution performs at scale rather than merely passing a compatibility suite.
Where differences appear, they are usually configuration rather than capability. Default settings for garbage collection or heap sizing can vary subtly between builds and version lines, and a workload tuned implicitly around an Oracle default may behave differently until the equivalent setting is applied explicitly. This is a tuning exercise, not a limitation, and surfacing it is exactly what a migration test phase is for. The same applies to the small set of historically Oracle only features, most of which have been contributed to OpenJDK and are now present in the open builds.
The practical conclusion is that feature and performance parity is the normal outcome of a Corretto migration, not the exception, provided the organisation runs a proper test phase and applies any needed configuration explicitly. The narrow cases where Oracle JDK remains necessary are genuine but rare, and they are identified during testing rather than discovered in production. The broader build comparison is in the OpenJDK versus Oracle JDK guide and the migration method in the migration guide.
The buyer side view
The practical takeaway is that Amazon Corretto removes the premise of the Oracle Java bill rather than negotiating it down. Because it is built from the same source, supported on a comparable cadence, and free at any scale, the case for paying Oracle's employee subscription has to rest on something other than the Java itself, and for most organisations there is nothing left to rest it on.
Treat Corretto as a serious default candidate when you plan a migration, particularly if your estate already runs on AWS. Validate compatibility for your specific applications, confirm your support requirements can be met without Oracle, and quantify the saving against your real employee cost. Start with the Java licensing pillar, compare alternatives in the OpenJDK guide, and use the Java advisory service to plan the switch.
Amazon Corretto vs Oracle Java: frequently asked questions
Is Amazon Corretto a replacement for Oracle Java?
Yes. Amazon Corretto is a free, production ready OpenJDK distribution built from the same source as Oracle JDK and is binary compatible for the vast majority of workloads. Switching to it removes the Oracle Java subscription cost.
Does Amazon Corretto get security updates?
Yes. Amazon provides quarterly security updates aligned with OpenJDK release cycles and offers long term support for its LTS versions, often beyond the free update window Oracle gives for its own builds.
Can I run Amazon Corretto outside AWS?
Yes. Corretto is free to run on any platform, in any cloud, or on premises. It is not restricted to AWS and creates no Oracle subscription obligation wherever it runs.