You’re a beginner in Cairo language, but you already knows solidity? This article will give you all the basis of Cairo (compared) to solidity in less than 3 minutes. Let’s start! What is Cairo ? Cairo is a new language for programming Starknet smart contracts. Starknet a L2 scaling solution for Ethereum. …

Free stuff is always a good thing! Even if the web2 products are selling our data without our consent, we are comfortable in using them, because they won’t charge us. Almost every interaction with the dApp involves a transaction which seems pretty complicated and intimidating for beginners because it prompts…

Multicall contracts have as function to execute multiple contract calls within one transaction. This is done via batching the inputs of the functions to another function, called Multicall. Reasons to do this are: Lower gas costs when bulk sending Lowering API calls to Infura/ RPC providers. Faster loading of web3…

Fractionalization is the concept of splitting up ownership of an NFT so that many people can receive benefits from it in a proportion to the amount they own. It’s a traditional concept that already exists today. …

My previous article highlighted a new initialization process used by EIP-2535: Diamonds as “A better way to initialize smart contracts.” This article will cover upgradeable smart contracts in more detail to defend my claim and provide insights. After reviewing upgradeability more generally, the following focus points will be discussed: OpenZeppelin…

Smart Contracts Design Patterns Series! Introduction Oracles are used to connect decentralized systems to the off-chain world. In other words, oracles are bridges between the off-chain and the on-chain systems. Based on the data flow and request directions, oracles can be categorized in four ways: — Pull based inbound oracle: Blockchains…

One exciting feature of Ethereum is the ability to prove consent directly between parties. In other words, you can easily validate that someone agreed to something without the need for a third party. As there is practically no limitation to the data being agreed to, this opens…

As NFT area is growing every day, more new mechanics and experiments are coming to the world of priceless pixels. One of the popular approaches during NFT launches is a Reveal toggle functionality. Reveal functionality stands for hiding NFT picture with some placeholder image initially. In this article we will…

One exciting feature of Ethereum is the ability to prove consent directly between parties. In other words, you can easily validate that someone agreed to something without the need for a third party. As there is practically no limitation to the data being agreed to, this opens up endless possibilities…

Smart Contracts Design Patterns Series! Introduction Smart contracts and transactions are transparent and verifiable on the Ethereum blockchain. However, in some cases, it could be useful to temporarily keep certain things hidden in the transactional data from the public. For example, in case of an election, displaying users’ choices could influence…

There are many options available to choose for storing NFTs’ metadata. But we can categorize all of those options into on-chain and off-chain categories. In this article, we first walk through these two options’ differences and then analyze the gas usage of minting one and multiple NFTs using each type. On-chain Data …

A Smart Contract provides the security, transparency, efficiency and trust to initiate an agreement inside a blockchain. Since it is executed inside a blockchain, it cannot access any external data such as weather data, or currency rates. Blockchain Oracles are designed to mitigate this issue. An oracle is a program…

Greetings dear readers! Today’s essay is the next in a series exploring creative solutions to challenges that an Auditor can encounter. In our previous article, we described Slither and how to use it; but today, we’d like to discuss fuzzing and the tool for it, Echidna. First and foremost, we…

As I mentioned in my previous post, the not propriety use of delegatecall function may lead to the gap of security. One of the problem is accidental to overwrite of variable, because delegatcall not use the name of variables, but their position in the storage. Let’s look at these…

This GitHub action can run Solidity Unit Tests as part of your continuous integration and deployment process. When coding a project, shifting the Solidity Unit Tests (SUT) to the GitHub side of things can optimize your workflow. Every time a push to the repo is made, the SUTs will run…

Here is the list of the most known Ethereum hacking tools used for auditing smart contracts: Slither: https://github.com/crytic/slither Mythril: https://mythril-classic.readthedocs.io/en/master/installation.html Mythix: https://mythx.io/ Remix solidity static analysis plugin: https://remix.ethereum.org Are they reliable? Can you REALLY hack a smart contract by pressing a button? We’ll see that. Note: If you’re on Windows…

Your good developer habits are leading you to write inefficient smart contracts. For typical programming languages, the only costs associated with state changes and computation are time and the electricity used by the hardware. However, for EVM-compatible languages, such as Solidity and Vyper, these actions explicitly cost money. This cost…

What if users could get rewarded for transactions and not pay gas? This tutorial will show you how! — How cool would it be if the users of your dApp did not need need to pay gas for transactions? What if they received rewards instead? MASS-ADOOOOOOOOOPTION! Here’s what we’ll cover In this tutorial, you will learn how to create dApps that support Meta-transactions and how to implement a Loyalty program to reward users…

How to Build a Flash loan Smart Contract that Borrows from Aave Pool. Borrow money the Blockchain way. If you're here to build a flash loan smart contract, this article presumes you already have the following set up: Metamask browser wallet Remix or VS code with solidity extension. Smart contract…