Deploy a Java bot (JDA, Javacord and others)

Java bots run as a single .jar file. The key is building a jar that already contains all its dependencies.

1. Build a "fat" jar

A normal jar build leaves dependencies out, and the bot fails on the server with NoClassDefFoundError. Build a jar with dependencies included instead.

Gradle (with the Shadow plugin):

plugins {
    java
    id("com.gradleup.shadow") version "8.3.5"
}

tasks.jar {
    manifest { attributes["Main-Class"] = "com.example.bot.Main" }
}

Then run ./gradlew shadowJar - your jar is in build/libs/ and ends in -all.jar.

Maven: use the maven-shade-plugin or maven-assembly-plugin with jar-with-dependencies, and set your Main-Class in the manifest.

2. Pick your Java version

On the panel's Startup tab, choose a Docker Image with the Java version you compiled for (JDA 5 needs Java 11+; Java 21 is a safe choice).

3. Upload and start

1. Upload the jar to the main folder using the file manager or SFTP.
2. On Startup, set the jar file variable to your jar's exact name, e.g. mybot-all.jar.
3. Click Start and watch the console.

Configuration and tokens

Java doesn't read .env files by itself. Either use a library like dotenv-java, or read a config.properties file you upload next to the jar. Never hard-code your token - see Environment variables for bots.

Memory

The JVM uses the memory your plan allows. If you see java.lang.OutOfMemoryError, your bot needs a bigger plan or has a memory leak (often an unbounded cache).

Common errors

Console message	Fix
no main manifest attribute	Set Main-Class in your build's jar manifest.
NoClassDefFoundError	You uploaded a thin jar - build the shaded/fat jar.
UnsupportedClassVersionError	The server's Java is older than your build target - pick a newer Docker image.

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Still stuck? Open a ticket on Discord - run /ticket in any channel, pick a department, and include your Server ID or Invoice ID so we can jump straight in.