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The Leading Open-Source Developer Library for Ethereum

Web3j makes it easy to build Ethereum applications with Java and Android

What is Web3j?

Web3j is a highly modular, reactive, type safe Java and Android library for working with Smart Contracts and integrating with clients (nodes) on the Ethereum network.



This allows you to work with Ethereum blockchains, without the additional overhead of having to write your own integration code for the platform.

Getting started with Web3j

Run the following in your terminal, then follow the onscreen instructions

curl -L | sh
web3j new
For Windows, follow these instructions.

Head to the docs for more information.

Start building with Web3j


Contribute to Web3j



Sirato integration

Web3j integrates seamlessly with the Sirato Blockchain Explorer


Type safe

Web3j provides full type safe access to your blockchain applications


Build tool integration

Plugins for leading build tools to simplify the developer experience


Versatile CLI

Create projects to work with new or import existing decentralised apps in a single command with the Web3j CLI


Powerful integration testing

Simple to use framework for automated integration testing against networks within your IDE


Commercially supported OSS

Web3j is 100% open source and maintained by Web3 Labs

Dedicated support from the creators of Web3j

Web3 Labs offer the following Web3j services 
  • Consulting services
    Strategic advisory and project delivery
  • Training workshops
    Hands-on workshops covering blockchain and smart contract development with Web3j
  • Commercial support
    Dedicated support for your blockchain applications

Enquire now

Some of the companies building with Web3j
We're grateful for the funding Web3j has received from
ethereum foundation

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