AdoptOpenJDK no longer exists as an active project — it migrated to Eclipse Temurin under the Eclipse Adoptium working group in 2021. If you are running AdoptOpenJDK in production today, you are running an unpatched JDK and should plan migration immediately. Amazon Corretto is an actively maintained, AWS-backed OpenJDK distribution that is a viable migration target, particularly for AWS-hosted workloads.
This article covers the historical context of both distributions, their key differences, and practical guidance for teams migrating off AdoptOpenJDK — whether to Corretto, Eclipse Temurin, or Azul Zulu. All three are free, TCK-certified OpenJDK distributions with active maintenance.
Azul Zulu is worth serious consideration as a migration target: it covers more Java versions than either Corretto or Temurin (including Java 6 and 7), provides Alpine Linux builds for containers , and offers an upgrade path to Azul Core commercial support without switching distributions.
What Is AdoptOpenJDK?
AdoptOpenJDK was a community-led project launched in 2017 to provide free, pre-built OpenJDK binaries for all major platforms — a gap created by Oracle’s tightening license policies. It quickly became one of the most popular community Java distributions, offering both HotSpot and Eclipse OpenJ9 JVM variants for Java 8, 11, and later versions.
In 2021, AdoptOpenJDK formally migrated to the Eclipse Foundation as the Eclipse Adoptium working group. The distribution was renamed Eclipse Temurin. AdoptOpenJDK binaries remain downloadable for legacy systems, but no new patches, no security fixes, and no new Java version support are being added. The adoptopenjdk.net website now redirects to adoptium.net.
What Is Amazon Corretto?
Amazon Corretto is Amazon Web Services’ no-cost, production-ready distribution of OpenJDK. Launched in 2018, Corretto is TCK-certified and provides LTS releases for Java 8, 11, 17, 21, and 25 with quarterly security patches. It ships as the default JDK on Amazon Linux 2 and Amazon Linux 2023, and AWS validates it against managed services including Lambda, ECS, and Elastic Beanstalk.
Unlike AdoptOpenJDK, Corretto is maintained by a single corporate entity with a clear roadmap and ongoing investment. It targets Linux (x64 and ARM64), Windows, and macOS. It does not provide OpenJ9 JVM builds (an AdoptOpenJDK differentiator), Java 6 or 7 builds, or Alpine Linux binaries. No commercial support tier is available for Corretto itself.
AdoptOpenJDK vs Amazon Corretto Comparison
| Feature | AdoptOpenJDK (Archived) | Amazon Corretto |
|---|---|---|
| License | GPLv2 + Classpath Exception | GPLv2 + Classpath Exception |
| Cost | Free (archived; no new patches) | Free (actively maintained) |
| Support | None (project retired 2021) | AWS patches; no enterprise SLA |
| LTS Versions | 8, 11 (unpatched) | 8, 11, 17, 21 |
| Performance | HotSpot or OpenJ9 JVM | HotSpot JVM, AWS/Graviton-tuned |
| Platforms | Wide (no longer maintained) | Linux, Windows, macOS (x64, ARM64) |
| TCK Certified | Was certified; now unverified | Yes |
Licensing and Cost
Both AdoptOpenJDK and Corretto use the GPLv2 with Classpath Exception license — commercially permissive and free for production use. The licensing terms are identical. The critical difference today is that AdoptOpenJDK is receiving no security patches, meaning teams running it are exposed to known CVEs without remediation. This is not a licensing risk but an operational and security risk.
The migration cost from AdoptOpenJDK to any current distribution is low. All TCK-certified distributions are binary-compatible within the same Java major version. Switching from AdoptOpenJDK 11 to Corretto 11, Temurin 11, or Zulu 11 typically requires only updating JAVA_HOME and reinstalling the JDK — application code does not need to be recompiled. JVM flags should be reviewed, but the migration itself is not a significant engineering effort.
For teams choosing a migration target, Azul Zulu and Azul Core offer the same free-tier licensing as Corretto and Temurin but add a commercial support upgrade path not commonly found among free distributions.
Performance and Support
AdoptOpenJDK offered a meaningful performance choice: HotSpot (optimized for peak throughput) or OpenJ9 (optimized for low memory footprint and fast startup). This differentiation made it popular for both traditional applications and cloud-native microservices. Corretto uses only HotSpot, with AWS-contributed patches improving performance on Graviton (ARM64) hardware specifically.
Teams migrating off AdoptOpenJDK’s HotSpot builds will find Corretto, Temurin, and Zulu to be functionally equivalent HotSpot distributions. Teams that used OpenJ9 should consider IBM Semeru Runtime, which continues the OpenJ9 distribution under IBM’s stewardship.
On support: AdoptOpenJDK had no commercial support — it was purely community-driven. Corretto similarly offers no formal SLA. Among the free distributions, only Azul Zulu has a commercial support upgrade path through Azul Core, making it the strongest choice for teams that may need formal JVM support in the future.
Which Should You Choose?
If you are on AdoptOpenJDK, migrate urgently — the project is archived and receiving no security patches. Your three primary migration targets are:
Eclipse Temurin is the direct successor and lowest-friction migration for most AdoptOpenJDK users. Same community values, same governance model, active maintenance under Eclipse Foundation.
Amazon Corretto is the right choice if you are on AWS infrastructure, Amazon Linux, or using AWS managed services. Pre-integrated, AWS-validated, and Graviton-optimized.
Azul Zulu is a strong choice for broader Java version coverage (including Java 6 and 7), Alpine Linux containers, multi-cloud portability, and the ability to add enterprise support without a JDK switch.
Frequently Asked Questions
Is AdoptOpenJDK still safe to use in production?
No. AdoptOpenJDK is archived and no longer receives security patches or bug fixes. Running it in production exposes systems to unpatched CVEs. Migration to an actively maintained distribution — Temurin, Corretto, or Azul Zulu — should be treated as a security priority.
What replaced AdoptOpenJDK?
Eclipse Temurin is the official successor to AdoptOpenJDK. The project migrated to the Eclipse Adoptium working group in 2021. Temurin provides the same HotSpot-based, free OpenJDK builds with ongoing active maintenance under Eclipse Foundation governance. adoptopenjdk.net now redirects to adoptium.net.
Can I migrate from AdoptOpenJDK to Corretto without recompiling?
Yes, when migrating within the same Java major version. Both are TCK-certified and binary-compatible. Switching from AdoptOpenJDK 11 to Corretto 11 requires only updating JAVA_HOME; no code recompilation is needed. Upgrading across major Java versions during migration may require code changes for deprecated APIs.
Does Corretto support the OpenJ9 JVM?
No. Amazon Corretto uses only the HotSpot JVM. AdoptOpenJDK supported both HotSpot and Eclipse OpenJ9. Teams dependent on OpenJ9’s memory footprint advantages should migrate to IBM Semeru Runtime, which continues OpenJ9 distribution under IBM. Temurin and Zulu also use HotSpot only.
Is Azul Zulu a good migration target from AdoptOpenJDK?
Yes. Azul Zulu is free, TCK-certified, and provides builds for a wide range of Java versions (6 through 25+) and platforms (including Alpine Linux). It is a drop-in replacement for AdoptOpenJDK’s HotSpot builds and offers an upgrade path to Azul Core commercial support for teams with formal SLA requirements.
Conclusion
AdoptOpenJDK served the Java community well during Oracle’s licensing transition, but it is now archived and replaced by Eclipse Temurin. Amazon Corretto is an excellent migration target for AWS-native teams, offering active AWS maintenance, LTS for Java 8 through 25, and tight Amazon Linux integration.
For teams needing broader Java version support, Alpine Linux compatibility, or a future-proof path to enterprise JVM support, Azul Zulu is the strongest migration target.