Smart Contracts and Web3 on Celo Tutorial Series

[Celo_Academy]

Introduction

Welcome to our comprehensive course designed to equip you with deep knowledge and practical skills in the domain of smart contracts, specifically tailored to the Celo platform. This syllabus will guide you through a structured, step-by-step path, transitioning from the basics of smart contracts to their advanced techniques and security aspects, while also exploring Web3 tools and real-world use cases.

Lesson 1: Understanding Smart Contracts

Introduction to Smart Contracts and Their Use Cases

Introduction Smart contracts are one of the most groundbreaking innovations in the blockchain ecosystem, transforming the way we conduct business and interact with one another. By automating complex processes and streamlining transactions, smart contracts have the potential to revolutionize a wide array of industries. In this post, we’ll introduce you to the fascinating world of smart contracts, explore some of their most compelling use cases, and discuss how you can harness their potential for…

Solidity Language Basics

Introduction In the rapidly evolving world of blockchain technology, Solidity has emerged as a leading programming language for creating smart contracts. As the backbone of Ethereum and many other blockchain platforms, Solidity is a versatile and powerful tool that can help you bring your smart contract ideas to life. In this post, we will introduce you to the basics of the Solidity language and provide you with the foundation needed to start building your own smart contracts. A Solid Foundat…

How to create your first smart contract on the celo blockchain

Introduction​ In this article, we will be building a crowdfunding smart contract using hardhat and deploying the smart contract to the Celo blockchain. Hardhat is a development environment for Ethereum software. With hardhat, you can write your smart contract, deploy them, run tests, and debug your code. Prerequisites​ For the purpose of this article, you will need to have basic knowledge of the solidity language and javascript. Requirements​ Having a code editor, VScode preferably, a chrom…

Lesson 2: Developing Smart Contracts

Unit Testing with Truffle and Celo

Introduction When creating decentralized applications that leverage smart contracts, it is important to ensure that there are little or no vulnerabilities to prevent an attacker from compromising your application. Unit testing helps you ensure that all functionalities in your contract are working as expected, and development environments like Truffle give you the same tools to help you write proficient tests for your contracts before final deployment. In this tutorial, you’ll create an exempl…

How to Create and Test Contract Calls with Celo and Hardhat

Introduction One of the most essential and helpful tools a blockchain developer has as an arsenal is making contract calls. When working on complex and multi-contract projects, it is very likely, that you won’t be deploying a single, smart contract file for the whole production. You might even deploy some contracts earlier than others. Making contract calls is a flexible way for deployed contracts to interact with others on the blockchain. This way, rather than having a messy long line of cod…

Solidity from Zero to Hero

Introduction Remix is one of the online programs that can be used to write and deploy the Solidity Smart contract on the Ethereum Blockchain. It is a powerful tool that can also be used to debug and prevent errors in the Solidity contracts. In this article, I’ll show you how to use Remix for writing and deploying, debugging Solidity smart contracts, and how to enter some Solidity commands. This tutorial assumes you are familiar with the basics of blockchain, the Ethereum platform, and programmi…

Implementing Multi-factor Authentication on Celo's blockchain Using Smart Contracts

[SAMPLE (147)] Introduction In this tutorial, we will implement a multi-factor authentication (MFA) on Celo’s blockchain using smart contracts. Multi-factor authentication is a security mechanism that requires users to provide two or more forms of authentication before gaining access to their accounts. It helps prevent unauthorized access and protects against cyber attacks. We will use Celo’s smart contract platform, which provides a secure and transparent way to implement MFA on the blockchai…

Best Practices for Writing Smart Contracts with Real World Examples

[SAMPLE (85)] Introduction The backbone of most web3 projects, if not all, is a well-thought-out smart contract architecture that handles the sensitive aspect of the application such as financial transactions, health records of patients in a hospital, game logic, and so on. Being a Celo developer, it is highly necessary to have a good engineering mindset when writing smart contracts to avoid costly mistakes that can put you at the mercy of bad actors. Prerequisites​ We are going to examine so…

Lesson 3: Advanced Smart Contract Techniques

Understanding Reentrancy Attacks And How To Protect Your Smart Contract Using OpenZeppelin

[SAMPLE (203)] Introduction Reentrancy attacks are a common security vulnerability in smart contracts, particularly those that handle Ether transactions on the Ethereum blockchain. This tutorial will provide a detailed explanation of reentrancy attacks, demonstrate a vulnerable smart contract, and show you how to use the OpenZeppelin library to protect your smart contract from such attacks. In this tutorial, we will explain reentrancy attacks, and provide a step-by-step guide for implementing…

Gas Optimization Techniques in Solidity on Celo

Introduction Optimizing smart contract performance is an essential aspect of blockchain development. Solidity, the most popular programming language for creating smart contracts on the Ethereum platform, provides several techniques to help improve the efficiency of your contracts. In this article, we’ll go over some of these techniques and how you can use them to improve the performance of your Solidity code. We’ll discuss how to save gas, avoid unnecessary computations, and improve contract re…

Building Celo DApp with Celocli without JavaScript Framework

Introduction When building web applications, the use of frameworks can make development easier by abstracting technical details. However, this can leave developers with a limited understanding of the underlying technology. In this tutorial, we will take a different approach by building a Celo DApp entirely on our local machine without using a JavaScript framework or an online IDE. This will allow beginners and intermediate developers to gain a deeper understanding of web development and blockch…

Lesson 4: Security in Smart Contracts

Interacting with Smart Contract on Celo using Web3py

[SAMPLE (151)] Introduction Interacting with the Ethereum protocol has been made easy with the advent of frameworks and libraries such as Web3py. Celo blockchain is compatible with the Ethereum Virtual Machine hence most tools for developing applications on the EVM are a good-to-go on Celo. For developers, it is important to be exposed to most of these tools if not all. Prerequisites​ I have designed this tutorial to help Celo-target developer understand how to use the web3py library to inter…

How to Write Upgradable Smart Contracts and Deploy to the Celo Blockchain

[SAMPLE (164)] Introduction The concept of upgradable smart contracts is very important for blockchain technology. It allows developers to create complex and useful smart contracts that can be upgraded over time. Upgradable smart contracts allow developers to change the functionality of a deployed smart contract after it has been published on the blockchain. This is done by separating the logic of the contract from its storage, allowing the logic to be upgraded while the storage remains intac…

Solidity Vulnerabilities - Signature Replay Attack

Introduction In the blockchain, a signature replay attack is an attack whereby a previously executed valid transaction is fraudulently or maliciously repeated on the same blockchain or a different blockchain. In this attack, the attacker can intercept a valid transaction and use the signature of that transaction to bypass security measures in order to perform the transaction again fraudulently. This article aims to explain scenarios where attackers can use the signature replay attack on our sol…

Prepare for Auditing Your Smart Contract

Introduction Smart contracts are self-executing contracts with the terms of the agreement between buyer and seller being directly written into lines of code. They can be used to automate and enforce the negotiation or performance of a contract. However, since smart contracts operate on a decentralized blockchain network, they are often subject to attacks and vulnerabilities that can compromise the security and functionality of the contract. To ensure the security and functionality of your smar…

Lesson 5: Web3 Integration and Use Cases

Connect and Interact with Celo using Web3React

[SAMPLE (186)] Introduction Building a user-centric blockchain-based application requires creating welcome experiences that make your users want to perform an action irrespective of known complexities or ones that may arise in the course of developing your product. There is a couple of libraries or provider that introduce different user experience. Here, you will learn about one of them. Prerequisites​ In this tutorial, I will walk you through the standard way of connecting to the Celo blockc…

Connect and Interact with Celo using Web3Onboard Library

[SAMPLE (161)] Introduction An essential feature of a blockchain-powered application is the ability to read and write to the blockchain. Unlike web2 databases, blockchains as immutable databases require agents that interface with them and the frontend. Such agents are called web3Provider. There are couple of them such as etherjs, web3js, web3Modal and so on. Prerequisites​ This tutorial will walk you through comprehensive guidelines and steps for connecting to the Celo blockchain using web3M…

Connect and interact with celo using web3Modal

[SAMPLE (188)] Introduction Building a user-centric blockchain-based application requires creating welcome experiences that make your users want to perform an action irrespective of known complexities or ones that may arise in the course of developing your product. There is a couple of libraries or provider that introduce different user experience. Here, you will learn about one of them. Prerequisites​ In this tutorial, I will walk you through the standard way of connecting to the Celo blockc…

Writing a Smart Contract to Handle Carbon Credits on The Celo Blockchain

[SAMPLE (160)] Introduction In this tutorial, we will design a smart contract in solidity to establish a Carbon Credit Token, an ERC20 token that will be used to track carbon credits on the Celo blockchain. This contract creates an ecosystem where users can buy and sell carbon credits, which are represented as tokens. The owner of the contract can mint and burn tokens. These actions increase or decrease the total supply of carbon credits. You can find the repository for this tutorial Here P…

Writing a smart contract to handle decentralized agricultural supply chain tracking using solidity on the celo blockchain

[SAMPLE (124)] Introduction In today’s digital world, the agriculture industry is one of the sectors experiencing significant transformation. The conventional methods of tracking products in supply chains are now being enhanced by blockchain technology. This tutorial is designed to introduce you to the concept of using blockchain for agricultural supply chain management. By the end of this tutorial, you will have a solid understanding of how to create a decentralized tracking system using Soli…

Lesson 6: Advanced Concepts and Best Practices

Proof of Work vs. Proof of Stake - A Comprehensive Comparison

Introduction In this article, we will provide a comprehensive comparison of proof of work and proof of stake, highlighting the key differences between the two algorithms and discussing their respective advantages and disadvantages. We will also examine the potential future developments of these algorithms and consider their potential use cases in various blockchain applications. Importance of Consensus Algorithms in Blockchain Technology Consensus algorithms are an essential component of bloc…

Exploring Solidity Low-Level Features - ABI Encoding and Opcodes

Introduction Solidity is a programming language for writing smart contracts on the Ethereum blockchain. It is an object-oriented, high-level language that is similar to JavaScript. However, Solidity also has low-level features that allow developers to interact with the Ethereum Virtual Machine (EVM) at a lower level. Two of these features are ABI encoding and opcodes. Prerequisites This tutorial is for already inclined and experienced developers with prior knowledge of smart contracts and the…

Blockchain Basics - An Introduction to Web3 Terms and concepts with Celo

[SAMPLE (175)] Introduction Oh, what the hell is this new Genz word going around, I don’t know this, Bitcoin and Ethereum all will just vanish, if these are your thoughts this article will help to clear misunderstandings, Blockchain is just the name of a train with coaches, each coach has unique transactional data with it, and once that coach is added to the train you cannot change or remove that, and in the train, every coach has people inside in it traveling and everyone is smart so they kn…

Introduction to Zero-Knowledge Technology and its Blockchain Applications

[SAMPLE (163)] Introduction Zero-knowledge technology is a term used to describe a method of cryptography that allows for the sharing of information without revealing any details about the data being shared. This makes it possible for two people who have never met before to communicate securely, even if they don’t know each other’s identities. The concept behind zero-knowledge technology was first developed by David Chaum in 1986 as “secret-sharing.” He showed how secure communication could b…

Understanding Utility and Security Tokens

Introduction Utility tokens are digital assets that lives on the blockchain and can be used to gain access to certain things, such as a game or a website. They do not give you ownership of a company or anything like that. On the other hand, security tokens are unique as they denote ownership, e.g., ownership of a company or a piece of property. If you have a security token, you may enjoy the privilege of voting on important decisions or even get compensated financially for owning a portion of a…

On-Chain Randomness with Celo using Subgraphs

Introduction In this tutorial, we will explore how subgraphs and randomness work in the Celo blockchain. This tutorial will cover the use of subgraph technology to monitor blockchain activity and how to integrate random elements into your blockchain application. By the end of this lesson, you’ll have a foundational understanding of how subgraphs and randomness can enhance your blockchain application and make it more engaging. Prerequisites This tutorial assumes prior knowledge of Hardhat and …

Understanding the Fundamentals of Auction Programming in Solidity

[SAMPLE (153)] Introduction Auction programming is a critical component of online buying and selling. It establishes auction rules and determines the highest bidder. The auction contract is a computer program that keeps track of all bids and ensures that the process is fair. In this article, we will look at the fundamentals of auction programming and its significance in the digital world. Prerequisites Understanding the fundamentals of blockchain technology and the concept of smart contracts …

Optimizing Gas Consumption in Celo Smart Contracts A Step-by-Step Guide

Introduction​ Gas is the unit of currency used to pay transaction fees on the Celo blockchain. This makes optimizing gas consumption an important consideration when developing smart contracts professionally. In this tutorial, we’ll explore some techniques for minimizing gas usage in Solidity smart contracts and demonstrate how to use the Hardhat gas reporter to test the efficiency of our code. Prerequisites​ To follow this tutorial, you will need: Basic knowledge of Solidity, Ethereum, and…

A Guide to Building and Deploying Upgradeable Contracts on CELO with Diamond Standard

[SAMPLE (11)] Introduction The Diamond Standard was articulated in EIP2535 and clearly defines a pathway for deploying multi facet smart-contracts that are modular, extensible and upgrade-able. Introduction In this tutorial, I introduce the diamond standard for writing modular and upgradeable smart contracts, and give a brief walkthrough of how to build an upgrade-able ERC20 token compatible contract, deploy to CELO, and perform an upgrade to the contract on-chain. Prerequisites​ This tutori…

Using Clones to Build and Cheaply Deploy Contracts on CELO at Scale

[SAMPLE (58)] Introduction​ The cost of deploying smart contracts on the blockchain is mostly proportional to the size of the runtime bytecode that ends up being stored on the blockchain, this is detailed in the Ethereum Yellow Paper, and is true for all EVM compatible blockchains, for which CELO is no exception. In this article, I present a novel approach for deploying contracts on-chain with minimal runtime bytecode, hence reducing the cost of your deployment significantly. To further driv…

How to Create a Decentralized Application Using React-Celo

Introduction In this tutorial, we will be building a decentralized application(Dapp) for the crowdfunding smart contract we created and deployed to the Celo blockchain previously. A decentralized application(Dapp) according to Wikipedia is an application that can run autonomously, typically through a smart contract, that runs through a decentralized computing, blockchain, or other distributed ledger. Simply put a Dapp is an application that runs without human intervention and is not owned by an…

Conclusion

By the end of this course, you’ll have gained a strong theoretical understanding and practical skills in smart contract development and security, with a specific focus on the Celo platform. You’ll be equipped to create efficient and secure smart contracts, develop your own decentralized applications, and navigate the rapidly-evolving world of blockchain technology. This course lays a robust foundation for you to innovate and build on the Celo platform, opening up new opportunities in the blockchain domain. Let’s embark on this exciting learning journey together!

[Phenzic]

This is actually a really Awesome Pathway, to get readers started on Celo…

Look forward to helping with more complex and Interesting Pathways too…

[Celo_Academy]

Thanks! I’ll be building a first draft of a few pathways then going through and editing to improve them. Trying to use as many of our sage tutorials as possible. Glad it’s looking good so far

[ishan.pathak2711]

I shared this link in my college group, it will surely help them

[EmiriDbest]

Wow…masterfully crafted. I will be sharing this around to my mentees.

[Balq]

This is cool

[jimohyusufolatunji4]

Wow, thanks so much for this… It will be very helpful to the beginners

[Qtech]

Nice pathway

[Clue]

I like they way they link to other tutorials

[bobelr]

My devs friends are much interested in learning smart contracts all their lives. Most of them are web2 dev. Will be directing them here.

[emmanuelikwuoma7]

Well curated content, big ups @Celo_Academy