App integration

ethereumjs (monorepo)

Core SDKs/libraries

SDK · Transaction signing · Merkle trees

ethereumjs/ethereumjs-monorepo @ethereumjs/rlp(2M)

The ethereumjs monorepo holds core JavaScript primitives for Ethereum, including transaction signing, an EVM implementation, RLP encoding, tries, and shared utilities. JavaScript builders import individual packages when they need protocol-level pieces rather than a full client library.

Related resources

Web3j

Lightweight, modular, reactive Java and Android library for Ethereum. JSON-RPC client API, wallet support, and auto-generated Solidity contract wrappers for deployment and interaction. Includes CLI, Maven/Gradle plugins, and ENS support.

web3.py

web3.py is the open source library that connects Python developers to Ethereum. The same team maintains more than a dozen additional building blocks including py-evm, eth-account, and eth-utils.

Ethers.js

Ethers.js is a compact TypeScript library for scripts, wallets, and services that need predictable JSON-RPC, ABI encoding, and signing helpers in Node or the browser.

Viem: TypeScript Interface for Ethereum

Viem is the most used modern TypeScript Interface for Ethereum. Viem provides robust, performant, and type-safe modules to be the foundation for building Web Applications, TypeScript Libraries, Wallets, Backends, Indexers, Scripts, and more, on top of Ethereum.

Nethereum

Nethereum is the .Net integration library for Ethereum, simplifying the access and smart contract interaction with Ethereum nodes both public like Geth (or your preferred client) L2 chains like Optimism, Arbitrum (or your preferred L2), any compatible EVM chain (Gnosis, etc) and permissioned chains like Quorum.

Rust Libp2p

rust-libp2p is the reference Rust implementation of libp2p's modular peer-to-peer stack used by Magi on the OP Stack, Lighthouse, Forest, and many other projects that need composable transports, security, pubsub, and discovery primitives for decentralized networking.