# LFDT-web3j/web3j

Lightweight Java and Android library for integration with Ethereum clients

Repository: https://github.com/LFDT-web3j/web3j
Canonical: https://ross.abutalabs.com/products/web3j
Homepage: https://www.web3labs.com/web3j-sdk
Language: Java
License: NOASSERTION
License Family: other
Topics: ethereum, blockchain, java, solidity, rxjava, android, smart-contracts, smart-contract-tools, ether, reactivex
Last push: 2026-08-18T13:44:09+00:00

## Health v2 (maintenance only)
Score: 91/100 (v2, computed 2026-09-02T17:46:02.011165+00:00)
- activity 98, release rhythm 78, longevity 100
- inputs: {"age_days": 3650, "days_push": 15, "days_rel": 65, "gap_med": 70.0, "n_releases_24m": 9}
- flags: no_license
- formula: round(0.45*activity + 0.35*rhythm + 0.20*longevity); archived -> min(score, 10)

## Adoption (not part of the score)
Stars 5391, forks 1770 (observed 2026-08-28T04:09:17.273111+00:00)

## What it is
Web3j is a lightweight, modular, reactive, type-safe Java and Android library for integrating with Ethereum clients and working with smart contracts. It provides a complete JSON-RPC client implementation, Java smart contract wrapper generation from Solidity, wallet support, and a bundled CLI.

## Use cases
- connect a Java application to an Ethereum node
- generate Java wrappers for Solidity smart contracts
- send transactions and deploy contracts from Android
- interact with Ethereum via Infura or Alchemy without running a node
- listen to blockchain events reactively with filters
- manage Ethereum wallets in Java
- resolve Ethereum Name Service names from JVM code

## When to choose
- you are building a JVM or Android application that needs Ethereum blockchain integration
- you want type-safe smart contract bindings generated from Solidity
- you prefer a reactive API for blockchain event streams
- you need a mature, widely adopted Java web3 library

## When to avoid
- you are building in JavaScript, Python, or another non-JVM language
- you need support for non-EVM blockchains like Solana or Bitcoin
- you want a full dapp frontend framework rather than a client library

## Facets
- artifact type: library
- maturity: active
- function: http-client, rpc, cli, sdk, serialization
- domain: blockchain, fintech, developer-tools, mobile-development
- platform: jvm, cli
- tags: ethereum, web3, smart-contracts, solidity, json-rpc, reactive, wallet, ens, cryptocurrency, android

## Member repositories
- LFDT-web3j/web3j (main) score 91

## Provenance
- Observed fields: from GitHub, fetched 2026-08-28T04:09:17.273111+00:00.
- Health v2: computed from the inputs above; adoption is never an input.
- Inferred fields (summary, facets, guidance): AI-extracted, prompt v1, taxonomy v1, on 2026-08-29T17:58:23.718974+00:00, confidence not recorded.
  - readme: https://github.com/LFDT-web3j/web3j (fetched 2026-08-28T04:09:17.273111+00:00, sha d4b2dc4025b2)
  - homepage: https://www.web3labs.com/web3j-sdk (fetched 2026-08-29T08:52:43.119802+00:00, sha b0a6bcceca02)
  - site_page: https://www.web3labs.com/about-us (fetched 2026-08-29T08:52:43.132791+00:00, sha 1180b4762f81)
  - site_page: https://www.web3labs.com/blockchain-explorer-chainlens-plans (fetched 2026-08-29T08:52:43.129148+00:00, sha f512c2234d89)
- Data as of 2026-08-30T08:39:29.467469+00:00.