Neow3j is a development toolkit that provides easy and reliable tools to build Neo dApps and Smart Contracts using the Java platform (Java, Kotlin, Android). It is an open-source project developed by the community and maintained by AxLabs.

Visit neow3j.io for more information and technical documentation.

If you are in need of a testnet or mainnet Neo node for your dApp but don't want to spend hours on setup, check out 1ClickNode.

Neow3j is composed of an SDK for dApp development and a devpack for smart contract development -- which also includes a compiler (JVM to NeoVM). The following sections describe how to get started with them! 🚀

To make use of all neow3j SDK features, add io.neow3j:contract to your dependencies.

Gradle

implementation 'io.neow3j:contract:3.22.1'

Maven

<dependency>
    <groupId>io.neow3j</groupId>
    <artifactId>contract</artifactId>
    <version>3.22.1</version>
</dependency>

Releases are available for Neo Legacy and Neo N3. The example above shows the newest release of neow3j for Neo N3. To use the latest release for Neo Legacy, use the version 2.4.0.

For smart contract development, you need the io.neow3j:devpack dependency. It provides all Neo-related utilities to write your first smart contract on the Neo blockchain!

Then, add the following dependency to your project.

Gradle

implementation 'io.neow3j:devpack:3.22.1'

Maven

<dependency>
    <groupId>io.neow3j</groupId>
    <artifactId>devpack</artifactId>
    <version>3.22.1</version>
</dependency>

Note: The devpack and compiler are only available for Neo N3. Thus, Java cannot be used to compile smart contracts that are compatible with Neo Legacy.

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Help the development of neow3j by sponsoring us using the following addresses:

• NEO Foundation & NEO Global Development (NGD)
• This project was strongly based on web3j latest on this commit. We are really thankful for it. 😃