Comparing the Architecture of MakerDAO, Yield, Compound, Aave and Euler — Borrowing is a cornerstone of Ethereum-based blockchain applications. With billions in assets loaned out, understanding how borrowing works is crucial for developers, architects, or researchers. Much like the evolution of programming paradigms, these DeFi applications have diverse architectural designs, reflecting changing priorities that range from security to efficiency and user…

On Friday 19th of May we were notified through immunefi about a bug in our Strategy contracts that would have allowed for a significant part of the funds from our LPs to be easily extracted. A war room was convened, and it was decided to use the emergency eject function…

How to find edge cases with echidna — Coding Smart Contracts is not for the faint of heart. Very recently, I participated in making the Yield Protocol go live. For those that haven’t heard of it, it is a fixed-rate borrowing and lending platform in Ethereum. …

Unlocking Ethereum for the masses — Everyone talks about “gas-less” Ethereum transactions because no one likes paying for gas. But the Ethereum network runs precisely because transactions are paid for. Then, how can you have “gas-less” anything? What is this sorcery? In this article, I’m going to show how to use the patterns behind “gas-less” transactions…

How to make your smart contracts cooperate safely — All but the simplest of Ethereum applications are composed of several smart contracts. This is because of a hard limit of 24KB in any deployed contract, and because your sanity will slip away as the complexity of a smart contract grows. Once you break down your code into manageable contracts…

A How To For Smart Contract Developers — When you vote for something, how do you know that anything will actually get done? How do you know that promises will be kept? In this article, I’m going to offer a glimpse into how blockchain can change democracy. With a blockchain democratic process, promises become actions. I’m not going…

Three example configurations for the new OpenZeppelin access control contract. — Restricting access to authorized users is really important in smart contracts. With $1 Billion locked in DeFi applications, you would really hope everyone knows what they are doing. Recently, I collaborated with OpenZeppelin to refactor the access control in their widely used openzeppelin-contracts repository. …

If it is not going to be used by a smart contract, dump it in an event — Anyone that is coding smart contracts as database tables is getting it wrong. That was me as well, until very recently. Developing blockchain solutions requires you to think differently about data, about control and about privacy. Some of the details are easy to grasp, such as currency being little more…

Put tokenized items for sale in a decentralized classifieds board — In this article, I’m going to show you how to code Craigslist for the Ethereum blockchain. Before Gumtree, eBay, and Craigslist, classified boards were mostly made of cork or paper. There were classifieds boards in school corridors, newspapers, streetlights, storefronts. All that changed with the internet. The number of people…