Free tool
Which Java does my Minecraft server need?
Pick your Minecraft version and see the Java it needs, based on Mojang’s own version files. Got an error? Paste it and we explain it.
FAQ
Java version checker FAQ
What does “UnsupportedClassVersionError” mean?
The server (or a plugin or mod) was built for a newer Java than the one running. The number in the error tells you which: 65 is Java 21, 69 is Java 25.
Can I always use the newest Java?
Usually not for old versions. Minecraft 1.16.5 and older, and Forge on those versions, often break on new Java. Use the one this tool shows.
Do players need Java to join?
No. The Minecraft launcher brings its own Java. Only the server needs the right one.
Is this tool free?
Yes. Free, no account, no limits for normal use. We host Minecraft servers and made these tools to help server owners.
More free tools: Server type quiz, Plugin checker, RAM calculator or all tools.
Free checklist
Server owner checklist
The 25 things to set up before you invite players: backups, permissions, anti-grief, performance. Plus one short email a month with server tips. No spam.
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