DeFi javascript web3js

Reading Chainlink price oracles from JavaScript

A common problem you may face in Ethereum programming is getting a price feed of digital currencies. Chainlink is an oracle platform that is used by many DeFi projects and incentives actors to publish on-chain several information like prices of tokens or price of Ether. in this tutorial we’ll learn how you can retrieve the […]


Getting data from the internet with Oraclize

Smart contracts can interact with data living in the blockchain but it is impossible to get informations from the web. Using Oraclize, we’ll see how your smart contracts can get data from outside the blockchain and execute any API call. Some use cases can be: It’s hard to generate completely random data on the blockchain can […]

blog offers free Ethereum archival node

Your project might require access to the Ethereum history. While Infura and similar node providers enable you to query in the past 50 blocks it’s hard for independent developers and small projects to get access to an archive node. Popular node provider offers this as an option to their monthly plans (will cost you 250$/month […]

blog debug Tests

Debugging your Ethereum transactions with Tenderly

Tenderly is a web app that has the mission to help developers and Ethereum companies in their building and maintaining dapps by providing real-time monitoring, alerting, and troubleshooting for Smart Contracts. In this example, we’ll see how Tenderly can be used to see what went wrong on a complex Ethereum transaction by analyzing it with […]

ABI data analytics erc20 javascript web3js

How to decode event logs in Javascript using abi-decoder

In this tutorial we’ll see how to decode and make sense of event logs generated by Ethereum transactions. This tutorial will guide you on getting a transaction receipt and getting the data related to one event in their original types using the abi-decoder library. For this tutorial you’ll need : the ABI of the smart […]

blog careers

Who’s hiring or looking for a job in Ethereum | June 2020

Are you looking for a job in the Ethereum/DeFi ecosystem or a company looking for great talents? We compiled a list of people looking for their next adventure in the Ethereum ecosystem. If you’re looking to get featured in the next edition fill this form. They are Hiring! Feel free to contact the following companies […]

blog DeFi erc20 javascript solidity

Making a flash loan with Solidity (Aave, Dy/Dx, Kollateral)

Flash Loans are loans that allow the borrowing of an asset, as long as the borrowed amount (and a fee) is returned before the end of the transaction. Those types of loans enable you to perform actions without using your funds for a really small percentage fee (0.09% at the time of writing on Aave […]

Arbitrage Bot DeFi DEX erc20 javascript web3js

Swap tokens with 1inch Exchange in JavaScript: DEX and Arbitrage part 2

For this tutorial will see how to execute a trade using 1inch DEX aggregator in Javascript with the web3.js library. At the end of the tutorial, you’ll know how to exchange ERC20 tokens and Ether directly on the Ethereum blockchain. This article is part 2 (part 1 here) of tutorials we started while using the […]

erc20 Getting started javascript

Waiting for a transaction to be mined on Ethereum with JS

In the previous tutorial we learnt how to send a transaction to an Ethereum smart contract, we’ll now see how to wait for a transaction to be mined and get it’s result. When you sbumit a transaction to the blockchain, you’ll receive the transaction hash of the new transaction. In order to wait for the […]

Getting started javascript

Compiling and deploying smart contracts in JavaScript and command line

This tutorial covers how to compile and deploy your smart contracts using JavaScript and Solidity comand line compiler solc. All our classes are made for beginners and advanced programmers to understand and build on the Ethereum blockchain. We really advise people to understand simple tools like solc compiler instead of jumping directly with complicated frameworks […]