Lendroid is an open-source, non-exploitative protocol designed for decentralized margin trading using ERC20 tokens on the Ethereum blockchain. By employing smart contracts, it eliminates the need for any third-party custodians, thereby mitigating the risk of hacks associated with custodial lending and margin trading. This platform facilitates a unified protocol along with a shared liquidity pool, enabling margin trading across a variety of both decentralized and centralized exchanges. Users can select from multiple business models, such as risk-free lending, operation of 'Harbour' or 'High Water' liquidity pools, or underwriting loans for a fee. The comprehensive ecosystem, which includes the user interface, is entirely open source, allowing for seamless launches of personalized lending decentralized applications (dApps). Developers benefit from fully audited smart contracts, ensuring security and trustworthiness, while users enjoy an unprecedented level of transparency and a sustainable approach to risk distribution. This innovative structure not only enhances user experience but also empowers individuals to engage in margin trading with confidence.