Corretto vs OpenJDK. The 2026 runtime call.

Amazon Corretto is a free, production supported OpenJDK distribution with eight year LTS coverage, and the choice against upstream OpenJDK builds comes down to patch longevity, support model, and cloud fit.

What is the difference between OpenJDK and a distribution?

OpenJDK is the open source project where Java is developed; a distribution is a tested, patched, supported binary built from that source. The OpenJDK project publishes reference builds, but those builds stop receiving updates when the next version ships.

That six month update horizon, visible in the JDK release archive, is the operational gap. Production estates need patches for years on a stable major version, which is exactly what downstream distributions exist to provide.

• Upstream reference builds: current version only, no LTS patch stream.
• Distributions: Corretto, Temurin, Zulu, and Liberica backport security fixes to LTS versions for years.
• The practical rule: production workloads run distributions; upstream builds are for development against the latest version.

What does Amazon Corretto actually provide?

Corretto is Amazon's no cost OpenJDK distribution with quarterly security updates and at least eight years of support per LTS release, per the Corretto support calendar. It is TCK certified, so it is drop in compatible with any compliant Java runtime.

The validation story is the differentiator. Corretto runs Amazon's own services, including every AWS Lambda Java function, which is production testing at a scale no enterprise replicates internally.

Where Corretto support has limits

Corretto support is community and AWS Support based; there is no standalone Corretto support contract for non AWS customers. Estates wanting a contractual Java support relationship independent of cloud spend look at Azul or BellSoft instead.

How do Corretto and upstream OpenJDK compare side by side?

On a current, actively developed application tracking the latest Java version, the difference is small. On a production estate sitting on Java 17 or 21 for years, the difference is the entire patch stream.

What the decision usually turns on

Cloud alignment and tooling. AWS estates get native packaging, container images, and platform integration with Corretto. Multi cloud and on premises estates often prefer Temurin's vendor neutral governance for exactly the same operational reasons.

Which runtime should your estate choose in 2026?

Choose Corretto when AWS is your primary platform, you want eight year LTS coverage at zero cost, and AWS Support already covers your production stack. Choose Temurin when governance neutrality matters across clouds. Choose a paid distribution only when you need contractual support with indemnities.

Whatever the landing zone, the move off Oracle Java SE subscriptions is the economic event. The runtime choice is secondary to exiting the per employee subscription metric cleanly, with usage evidence archived before the switch.

• AWS first estates: Corretto by default.
• Mixed and on premises estates: Temurin by default, Corretto fully viable.
• Contractual support needs: Azul or BellSoft, priced against the risk they cover.

Where the common advice on free Java distributions is wrong

The standard advice, often originating from vendors selling Java support, says free distributions like Corretto are fine for development but production estates need a paid support contract. We disagree. In roughly 40 to 60 Java engagements Fredrik Filipsson advised in 2024 to 2025, estates running Corretto or Temurin in production logged no stability incident that a support contract would have changed, while the subscription quotes they avoided ran into seven figures. The buyer side move is to buy support for the workloads that demonstrably need indemnified response, which is a small minority, and run the validated free distributions everywhere else. Paying for Java insurance estate wide is the vendor's business model, not your risk profile.

What the engagement data shows

Three cuts of our advisory engagement file frame the size of the opportunity.

What to do next

Five moves turn this analysis into a lower invoice on the next renewal.

A sequence you can run this quarter

1. Inventory Java versions, vendors, and install counts across the estate.
2. Classify workloads by platform: AWS first, multi cloud, or on premises.
3. Pick the default distribution: Corretto for AWS estates, Temurin for mixed.
4. Pilot the migration on a representative application set for one quarter.
5. Archive Oracle Java usage evidence before subscription exit.
6. Roll out by platform team with quarterly patch adoption tracked.

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Frequently asked questions

Is Amazon Corretto really free for production use?

Yes. Corretto is free for production under an open source license, with quarterly security updates and at least eight years of support per LTS release. There is no license fee and no usage based charge from Amazon.

What is the difference between Corretto and OpenJDK?

OpenJDK is the upstream project and reference build; Corretto is Amazon's downstream distribution of it. The practical difference is the patch stream: upstream builds stop updating when the next version ships, while Corretto backports fixes for eight years.

Is Corretto compatible with Oracle Java?

Yes. Corretto is TCK certified, meaning it passes the same compatibility test suite as Oracle's JDK. Under 5 percent of applications needed any remediation in the migrations we benchmarked, mostly build pipeline adjustments.

Does Corretto only work on AWS?

No. Corretto ships for Linux, Windows, macOS, and containers, and runs anywhere. The AWS alignment shows in tooling and validation scale rather than any platform restriction.

Should you pick Corretto or Eclipse Temurin?

AWS first estates default to Corretto for the platform integration; multi cloud and on premises estates often prefer Temurin's vendor neutral governance. Both are TCK certified and free, so the decision is operational, not technical.

Do you need a paid Java support contract for production?

Usually not estate wide. Estates running Corretto or Temurin in production logged no incident a contract would have changed across our 2024 to 2025 file. Buy contractual support only for workloads needing indemnified response.