Tools
Which jar is this?
Paste the SHA-256 of a jar and we will tell you exactly what it is: which software, which Minecraft version and which build. Use it to identify a server you inherited, or to check that a download really is what the publisher released.
How to get the checksum of your jar
The hash is worked out on your own machine. Run one of these in the folder that holds the jar, then paste the 64 characters it prints into the box above.
Linux sha256sum server.jar macOS shasum -a 256 server.jar Windows certutil -hashfile server.jar SHA256
If the hash matches a build here, the file is byte for byte the one that publisher released. If it does not match, the file has been changed since it was published, or it came from a build we hold no checksum for.
Common questions
Do I have to upload my jar?
No, and you should not have to. The hash is computed on your own machine by the command above; the only thing that reaches this site is 64 hex characters. A server jar can be hundreds of megabytes and is not ours to hold.
What if there is no match?
It means we have no record of that exact hash. That happens for a modified or repackaged jar, but also for perfectly good builds from projects that never publish a checksum, and for builds older than our coverage. A miss is not proof that anything is wrong.
Can I use an MD5 or SHA-1 instead?
No. Publishers give us SHA-256, so that is what we can match against. MD5 and SHA-1 are also both considered broken for verifying that a file has not been tampered with.
Why would I check a jar at all?
Two reasons. You inherited a server and want to know what is actually running on it, or you downloaded a jar from somewhere other than the publisher and want to confirm it is the real thing before you run it on a machine with your players' data on it.