Amazon Corretto vs OpenJDK comparison.

OpenJDK is a project. Corretto is a downstream distribution. The difference matters when you are picking a runtime for production.

Once an estate decides to leave Oracle Java SE Universal Subscription, the next question is which OpenJDK distribution to use. Amazon Corretto sits in the top four every time.

Corretto is a downstream OpenJDK build maintained by AWS. The source is OpenJDK. The build, the testing, the patch cadence, and the LTS commitment come from Amazon.

This page sets out the comparison. What OpenJDK is, what Corretto adds, how the two compare side by side, and how to pick the right fit for your estate.

The OpenJDK baseline

OpenJDK is the upstream open source Java project. Oracle, AWS, Microsoft, Azul, BellSoft, Red Hat, and the community all contribute.

What OpenJDK actually is

OpenJDK is the source code. It is not a packaged binary. A user does not run OpenJDK directly. A user runs a build of OpenJDK produced by a vendor.

• Source. The OpenJDK project at openjdk.org.
• Builds. Vendor produced binaries that ship from that source.
• Patches. Security fixes backported into vendor builds on a defined cadence.

OpenJDK licensing

OpenJDK ships under the GNU General Public License version two with the Classpath Exception. Free for commercial use. No usage tracking. No employee count metric.

Distribution model

Vendors build OpenJDK from source, run their own test suites, sign the binaries, and publish them under their own brand. Corretto, Temurin, Microsoft Build, and Azul Zulu all follow this model.

Amazon Corretto in detail

Corretto is the OpenJDK build that AWS uses in production. Lambda, EKS, EC2 Java workloads. The scale of internal validation is large.

Versions and LTS

Corretto ships builds for Java 8, 11, 17, and 21 in 2026. Each LTS version is supported for at least eight years from initial release.

Patch cadence

Corretto releases quarterly security patches aligned with the Oracle Critical Patch Update window. Out of band patches ship for critical vulnerabilities.

Platform coverage

Corretto runs on Linux, macOS, Windows, and ARM. Native ARM builds are first class. Containers ship from the Amazon Linux base image.

Support and licensing

Corretto is free. AWS does not sell paid support. Commercial support for Corretto inside AWS comes through standard AWS support plans.

Side by side

OpenJDK as a project is not directly comparable to Corretto as a distribution. The real comparison is Corretto against the other credible distributions.

Patch cadence

All four credible distributions ship security patches on the quarterly OCPU calendar. Corretto and Microsoft Build often ship within hours of the OCPU. Temurin and Zulu typically ship the same day.

LTS coverage

Corretto, Azul Zulu, and BellSoft Liberica all commit to eight years of LTS support. Temurin follows the community Adoptium LTS timeline. Microsoft Build commits to at least six years of LTS.

Cost

All four distributions are free for production use. Azul and BellSoft sell paid support contracts. Corretto, Temurin, and Microsoft Build do not.

OpenJDK is the source code. Corretto is the binary that runs Lambda. Pick the binary. Move on.

Decision framework

The decision is rarely about features. It is about cloud fit, support model, and the operating profile of the team running Java in production.

Cloud weighting

AWS heavy estates pick Corretto. Azure heavy estates pick Microsoft Build. Mixed estates pick Temurin. Regulated estates wanting paid support pick Zulu or Liberica.

Support model

Free distributions ship security patches but do not provide named support contacts. Azul and BellSoft sell that contact for a per server fee. Most enterprise estates can run without it.

Team profile

Larger Java estates often standardize on one distribution to simplify packaging and patching. Smaller estates can mix distributions by workload without operational pain.

Operating profile

Whichever distribution you pick, the operating profile looks similar.

Packaging

Distribute through existing channels. SCCM, Jamf, Intune, Ansible, container base images, or Homebrew.

Vulnerability monitoring

Subscribe to the vendor security advisories. Patch on the OCPU cadence. Log version state across the estate for audit defense.

Version policy

Most estates pin to one LTS release. Java 17 is the dominant pick in 2026. Java 21 adoption is accelerating.

Suggested reading

• Oracle Java vs OpenJDK comparison. Cross vendor reading from the wider library.
• Oracle Java vs OpenJDK decision guide. Cross vendor reading from the wider library.
• OpenJDK end of life roadmap 2026. Cross vendor reading from the wider library.

What to do next

1. Confirm the cloud weighting of your Java estate. AWS, Azure, mixed, or on premises.
2. Shortlist two distributions that fit the cloud profile and the support model.
3. Pilot the top choice on a non production workload for thirty days.
4. Compare patch latency against the OCPU calendar.
5. Validate native ARM and container support if relevant.
6. Standardize on one LTS release across the estate.
7. Roll out through existing deployment tooling.
8. Document the OpenJDK operating playbook for ongoing patching and version policy.

Frequently asked questions

Is Corretto really free for production?

Yes. Corretto ships under the OpenJDK license. Free for commercial production use, with no usage tracking and no employee count metric.

Do we need an AWS account to use Corretto?

No. Corretto runs on any Linux, macOS, Windows, or ARM machine. AWS is not required.

How is paid support handled?

AWS does not sell a Corretto support contract directly. Support comes through standard AWS support plans when Corretto runs on AWS. Outside AWS, most estates run without paid support.

How does Corretto compare to Oracle Java SE?

Binary compatible for almost every workload. Same security patches. Quarterly cadence. No employee count metric and no Oracle audit exposure.

What about Java 8?

Corretto ships Java 8 builds. LTS coverage continues into the late 2020s. Many enterprise estates still run Java 8 in production.

Can we mix Corretto with another distribution?

Yes. The binaries are interchangeable. Many estates run Corretto on AWS workloads and Temurin or Microsoft Build elsewhere.