Ethers.js

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 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.

noble cryptography is a family of minimal-dependency TypeScript cryptographic libraries that prioritize readable source, signed releases, and transparent npm builds, and they underpin most modern JavaScript wallets including MetaMask, Rabby, Rainbow, and many SDKs across the ecosystem.

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 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 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.