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Azul Zulu vs IBM Semeru Runtime Open Edition: catalog facts
Azul Zulu	IBM Semeru Runtime Open Edition
Best for: Developers who need a specific Java version installed on any desktop OS	Best for: Java developers wanting an OpenJ9-based OpenJDK build
Free The Zulu builds of OpenJDK are free to download from Azul.	Free Free to download, with optional paid enterprise support from IBM.
Windows, macOS, Linux, Command line	macOS, Command line
Builds for every current long-term Java version, back to Java 8 Packages for Windows, macOS and Linux from one page All 3 strengths for Azul Zulu Builds for every current long-term Java version, back to Java 8 Packages for Windows, macOS and Linux from one page Based directly on OpenJDK	Uses the Eclipse OpenJ9 JVM instead of HotSpot Drop-in replacement for other OpenJDK builds All 3 strengths for IBM Semeru Runtime Open Edition Uses the Eclipse OpenJ9 JVM instead of HotSpot Drop-in replacement for other OpenJDK builds Free binaries with optional commercial support
A runtime and toolkit, with no graphical tools of its own Many vendors ship near-identical OpenJDK builds, so the choice is often about support	Only useful to people running or developing Java software OpenJ9 tuning options differ from HotSpot
Downloadable app	Downloadable app
Open source	Open source
License: GPL-2.0 with Classpath Exception	License not stated
Not stated if an account is needed	No account needed
Offline features available	Offline features available
Official website Full listing and sources Sources for Azul Zulu azul.com/downloads Catalog checked October 2, 2026	Official website Full listing and sources Sources for IBM Semeru Runtime Open Edition developer.ibm.com/languages/semeru-runtimes Catalog checked October 1, 2026

“Not stated” means we have not confirmed it. Features can vary by device and plan.