OpenZeppelin Contracts is a library for secure smart contract development.

Modern, opinionated, and gas optimized building blocks for smart contract development.

Examples of Solidity security issues

Simple, intentionally-limited versions of web3 protocols & apps.

Basic string utilities for Solidity

DeFi SDK Makes Money Lego Work

Dai Stablecoin System

1inch Protocol – fully on-chain DeFi aggregation protocol

Proxy contract to compose Ethereum transactions

Safe arithmetic

Multi-Sig Wallet v2, supporting original Wallet.sol methods with additional confirmAndExecute improvements to allow for single-transaction signing by multiple owners.

Flash lending smart contracts

ERC-4626 wrappers for common yield-generating platforms

Reference implementations for ERC20 Flash Loans and Flash Mints

GOO (Gradual Ownership Optimization) Issuance.

A Simple-To-Install Solidity Flattener