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 the Ethereum blockchain, without the additional overhead of having to write your own integration code for the platform.

The Java and the Blockchain talk provides an overview of blockchain, Ethereum and web3j.


  • Complete implementation of Ethereum's JSON-RPC client API over HTTP and IPC
  • Ethereum wallet support
  • Auto-generation of Java smart contract wrappers to create, deploy, transact with and call smart contracts from native Java code (Solidity and Truffle definition formats supported)
  • Reactive-functional API for working with filters
  • Ethereum Name Service (ENS) support
  • Support for Parity's Personal, and Geth's Personal client APIs
  • Support for Infura, so you don't have to run an Ethereum client yourself
  • Support for ERC20 and ERC721 token standards
  • Comprehensive integration tests demonstrating a number of the above scenarios
  • Command line tools
  • Android compatible
  • Support for JP Morgan's Quorum via web3j-quorum


It has five runtime dependencies:

It also uses JavaPoet for generating smart contract wrappers


You can help fund the development of web3j by donating to the following wallet addresses:

Ethereum 0x2dfBf35bb7c3c0A466A6C48BEBf3eF7576d3C420

Bitcoin 1DfUeRWUy4VjekPmmZUNqCjcJBMwsyp61G

Commercial support and training

Commercial support and training is available from web3labs.