The future of a Decentralized Etherscan
Learn how to use the new Sourcify infrastructure today
We all love Etherscan . It's a great tool to interact with contracts, read the source codes or just see the status of your transactions. But unfortunately as great as it is, we should not forget that it's a centralized service. The website could be taken down any day. This kind of defeats the...
Integrating the 0x API into your contracts
How to automatically get the best prices via 0x
How can you add 0x to your contracts to automatically convert between tokens? We have done this in a similar fashion before with Uniswap and Balancer . The 0x API has a bit of a twist. Let's take a look why... Why you want 0x in your contracts? It's simple: Okay, but seriously. Let's see why the...
How to build and use ERC-777 tokens
An intro to the new upgraded standard for ERC-20 tokens
The new upgraded standard for ERC-20 tokens is becoming more and more popular. It's fully backwards compatible, you can easily create one using the Openzeppelin contracts and there are many interesting new features not available in ERC-20. Should you upgrade from ERC-20? Well let's look into what...
COMP Governance Explained
How Compound's Decentralized Governance is working under the hood
You might have heard about the COMP token launch. With a current market cap of over 350 million USD, the token has accumulated massive value. But what is the actual utility of COMP? It's a governance token. Compound being a fully decentralized system (or at least on the way towards it), has a...
How to prevent stuck tokens in contracts
And other use cases for the popular EIP-165
Do you remember the beginning of the Dark Forest story? If not, let's look at it again: Somebody sent tokens to a smart contract that was not intended to receive tokens. This perfectly illustrates one of the issues not only with ERC-20 tokens, but generally with smart contracts. How can we find...
Understanding the World of Automated Smart Contract Analyzers
What are the best tools today and how can you use them?
As we all know, it's very difficult writing a complex, yet fully secure smart contract. Without the proper methods, chances are you will have many security issues. Automated security testing tools already exist and can be a great help. One of the main challenges for these tools is to maximize...
A Long Way To Go: On Gasless Tokens and ERC20-Permit
And how to avoid the two step approve + transferFrom with ERC20-Permit (EIP-2612)!
It's April 2019 in Sydney. Here I am looking for the Edcon Hackathon inside the massive Sydney university complex. It feels like a little city within a city. Of course, I am at the wrong end of the complex and I realize to get to the venue hosting the Hackathon I need to walk 30 minutes to the...
Smart Contract Testing with Waffle 3
What are the features of Waffle and how to use them.
Waffle has been a relatively recent new testing framework, but has gained a lot of popularity thanks to its simplicity and speed. Is it worth a try? Absolutely. I wouldn't run and immediately convert every project to it, but you might want to consider it for new ones. It's also actively being...
How to use xDai in your Dapp
Deploying and onboarding users to xDai to avoid the high gas costs
Gas costs are exploding again, ETH2.0 is still too far away and people are now looking at layer 2 solutions. Here's a good overview of existing layer 2 projects: https://github.com/Awesome-Layer-2/awesome-layer-2 . Today we will take a closer look at xDai as a solution for your Dapp. What are...
Stack Too Deep
Three words of horror
You just have to add one tiny change in your contracts. You think this will take you only a few seconds. And you are right, adding the code took you less than a minute. All happy about your coding speed you enter the compile command. With such a small change, you are confident your code is...
Integrating the new Chainlink contracts
How to use the new price feeder oracles
By now you've probably heard of Chainlink. Maybe you are even participating the current hackathon ? In any case adding their new contracts to retrieve price feed data is surprisingly simple. But how does it work? Oracles and decentralization If you're confused about oracles, you're not alone. The...
TheGraph: Fixing the Web3 data querying
Why we need TheGraph and how to use it
Previously we looked at the big picture of Solidity and the create-eth-app which already mentioned TheGraph before. This time we will take a closer look at TheGraph which essentially became part of the standard stack for developing Dapps in the last year. But let's first see how we would do...
Adding Typescript to Truffle and Buidler
How to use TypeChain to utilize the powers of Typescript in your project
Unlike compiled languages, you pretty much have no safeguards when running JavaScript code. You'll only notice errors during runtime and you won't get autocompletion during coding. With Typescript you can get proper typechecking as long as the used library exports its types. Most Ethereum...
Integrating Balancer in your contracts
What is Balancer and how to use it
What is Balancer? Balancer is very similar to Uniswap . If you're not familiar with Uniswap or Balancer yet, they are fully decentralized protocols for automated liquidity provision on Ethereum. An easier-to-understand description would be that they are decentralized exchanges (DEX) relying on...