Amazon Corretto 21

Amazon Corretto 21 is Amazon's no-cost, long-term-supported distribution of OpenJDK 21. It provides a Java Development Kit for developers and users running applications that require Java 21, with a JVM, compiler and standard development, diagnostic and packaging tools. This entry is specifically the corretto@21 Mac cask, not the unversioned Corretto cask or another Java major release.

Features and intended use

• Compile and run Java 21 applications with the OpenJDK toolchain.
• Use Java 21 language/runtime features, including virtual threads and modern language improvements, where the application supports them.
• Obtain Amazon-maintained security, stability and performance updates.
• Use standard Java tools such as java, javac, jar, javadoc and diagnostic utilities.
• Develop locally or deploy compatible applications on other supported platforms using separate builds.

Corretto is a runtime and development kit, not a graphical code editor, an AWS cloud account or a bundled application server. Amazon certifies Corretto with the Java Technology Compatibility Kit. Compatibility with Java SE does not guarantee that an application depending on a different Java major version, proprietary extensions or native libraries will work unchanged.

Install and select the JDK

Install with brew install --cask corretto@21, or use the official architecture-appropriate Mac PKG installer. AWS's guide requires administrator permissions for installation and removal and places the JDK under /Library/Java/JavaVirtualMachines/. The captured cask lists no additional formula dependency or explicit conflicting cask.

Multiple JDKs can coexist, but your shell, IDE and build tools must select the intended one. AWS documents /usr/libexec/java_home --verbose for listing installed JDK paths and JAVA_HOME=/Library/Java/JavaVirtualMachines/amazon-corretto-21.jdk/Contents/Home for selecting Corretto 21. Setting JAVA_HOME replaces that environment variable's previous value; it does not remove other JDKs. Configure the IDE and build-tool toolchain separately when needed, and ensure PATH resolves the matching tools. Verify the reported Java vendor, major version and architecture before relying on a build.

Back up project/toolchain configuration and test applications before updating. Removing a JDK can break applications pointing at its path; inspect dependencies and selected runtimes first. The package does not require enabling Accessibility, Screen Recording or Full Disk Access for ordinary Java compilation. Applications run by Java can have their own file, network and macOS permission requirements.

Platforms and compatibility

The latest three recorded Corretto 21 builds target macOS 14 or later on x86_64 and aarch64. AWS's current FAQ supports macOS versions still receiving Apple security patches and currently lists Sonoma 14 or later. The generic installation guide still has a macOS 11-or-later heading; that procedural guide is not a promise that the current build supports every old OS. Use the current release target/support information when choosing a version.

The captured current download is the Apple Silicon aarch64 PKG. Intel Macs use the separate x64 package. These Mac builds are 64-bit; do not infer a 32-bit Mac build from older Corretto/Windows offerings. Native JNI libraries and other application dependencies must match the selected architecture. Windows and Linux have their own builds, dependency requirements and packaging; Linux headless/RPM changes are not Mac prerequisites.

JavaFX is not bundled with Corretto 21. Applications requiring JavaFX need an appropriate separate OpenJFX dependency and compatible native modules. Do not transfer historical Corretto 8 JavaFX inclusions to this Java 21 entry. A JVM also does not automatically supply application libraries, Maven/Gradle or an IDE.

Versions and maintenance

The full Corretto build identifier matters. The latest records are 21.0.12.12.1, 21.0.12.9.1 and 21.0.12.8.1; they are separate maintenance builds even though they share a Java 21.0.12 family number. Their official changelogs describe different timezone, Mac metadata, upstream baseline and security changes. Keep the vendor build number when comparing installed packages or troubleshooting.

AWS currently lists Corretto 21's last planned update as July 2030 and end of life as October 2030. Review the current support calendar before long-term deployment. Regular updates do not substitute for testing your own application and third-party libraries. Local compilation and execution can work offline once the JDK and project dependencies are present; downloads, updates and cloud services need connectivity.

Cost, accounts and license

Corretto is distributed without charge under GNU GPL version 2 with the Classpath Exception, with applicable notices for included components. An AWS account, cloud subscription or AWS Support Plan is not required to download the public JDK or run local Java programs. Corretto's no-cost long-term updates are distinct from optional paid AWS support assistance. Deploying on AWS or using other cloud services can require accounts and incur their normal charges.

The official 21.0.12.12.1 Apple Silicon Mac PKG is 200,717,360 bytes, verified through HTTP HEAD metadata. Installed storage and project dependencies require additional space. Intel package size may differ. The JDK itself does not upload your project merely because it is Amazon-branded; network behavior depends on the Java applications and tools you run.

Sources: Corretto overview, Official FAQ, Mac installation guide, Java 21 repository and releases.

Historical Corretto family workflow

The publisher's 2019 tutorial demonstrates installing Corretto 8 and running Tomcat on Linux ARM64. The accompanying browser screenshot shows Corretto 8.232 runtime properties after that workflow. It illustrates the Corretto product family, not Corretto 21, a current Mac installation, or a bundled application server. Use the Corretto 21 installation instructions above for this package. Official AWS tutorial.