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Java implementation of the Ethereum yellowpaper. For JSON-RPC and other client features check Ethereum Harmony
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Welcome to ethereumj

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EthereumJ is a pure-Java implementation of the Ethereum protocol. For high-level information about Ethereum and its goals, visit The ethereum white paper provides a complete conceptual overview, and the yellow paper provides a formal definition of the protocol.

We keep EthereumJ as thin as possible. For JSON-RPC support and other client features check Ethereum Harmony.

Running EthereumJ

Adding as a dependency to your Maven project:
or your Gradle project:
   repositories {
       maven { url "" }
   compile "org.ethereum:ethereumj-core:1.6.+"

As a starting point for your own project take a look at

Building an executable JAR
git clone
cd ethereumj
cp ethereumj-core/src/main/resources/ethereumj.conf ethereumj-core/src/main/resources/user.conf
vim ethereumj-core/src/main/resources/user.conf # adjust user.conf to your needs
./gradlew clean shadowJar
java -jar ethereumj-core/build/libs/ethereumj-core-*-all.jar
Running from command line:
> git clone
> cd ethereumj
> ./gradlew run [-PmainClass=<sample class>]
Optional samples to try:
./gradlew run -PmainClass=org.ethereum.samples.BasicSample
./gradlew run -PmainClass=org.ethereum.samples.FollowAccount
./gradlew run -PmainClass=org.ethereum.samples.PendingStateSample
./gradlew run -PmainClass=org.ethereum.samples.PriceFeedSample
./gradlew run -PmainClass=org.ethereum.samples.PrivateMinerSample
./gradlew run -PmainClass=org.ethereum.samples.TestNetSample
./gradlew run -PmainClass=org.ethereum.samples.TransactionBomb
Importing project to IntelliJ IDEA:
> git clone
> cd ethereumj
> gradlew build


  • File -> New -> Project from existing sources…
  • Select ethereumj/build.gradle
  • Dialog “Import Project from gradle”: press “OK”
  • After building run either org.ethereum.Start, one of org.ethereum.samples.* or create your own main.

Configuring EthereumJ

For reference on all existing options, their description and defaults you may refer to the default config ethereumj.conf (you may find it in either the library jar or in the source tree ethereum-core/src/main/resources) To override needed options you may use one of the following ways:

  • put your options to the <working dir>/config/ethereumj.conf file
  • put user.conf to the root of your classpath (as a resource)
  • put your options to any file and supply it via -Dethereumj.conf.file=<your config>
  • programmatically by using SystemProperties.CONFIG.override*()
  • programmatically using by overriding Spring SystemProperties bean

Note that don’t need to put all the options to your custom config, just those you want to override.

Special thanks

YourKit for providing us with their nice profiler absolutely for free.

YourKit supports open source projects with its full-featured Java Profiler. YourKit, LLC is the creator of YourKit Java Profiler and YourKit .NET Profiler, innovative and intelligent tools for profiling Java and .NET applications.

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ethereumj is released under the LGPL-V3 license.

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