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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 OpenEthereum's Personal, and Geth's Personal client APIs
  • Support for Alchemy and Infura, so you don't have to run an Ethereum client yourself
  • Support for ERC20 and ERC721 token standards
  • Support for HSM
  • 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

Commercial support and training

Commercial support and training is available from Web3 Labs.