Patrick Collins

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And what’s the oracle problem? Why can’t blockchains themselves make API calls?

Blockchain Oracle — The Oracle Problem
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1. What Is an Oracle?

A is any device or entity that connects a deterministic blockchain with off-chain data.

There is a lot to unpack in that one sentence.

To understand what blockchain oracles are and why we need them, let’s go back to one of the core features of a blockchain — decentrality.

The problem with blockchains

Since the blockchain has its distributed ledger nature, each node in the network has to be able to find the same end result given the same input. Otherwise, when a node looks to validate a transaction another node makes, it would end up with a different result. …

FreeCodeCamp has just released an entire that goes over everything a successful smart contract needs to learn, all jam-packed into 1 free 16-hour course.

Taught, by yours truly!

Each section comes with either or all available in the giant mega GitHub repo associated with the course:

👩‍💻 GitHub Repo:

The GitHub Repo has everything you need to be successful in the tutorial and learn solidity.

A dive into the world of Solidity

Signing a contract
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You may want to upgrade your smart contract for a number of reasons. You might want to fix a bug, add new features, or anything else. This article will teach you about the different things you need to know, conventional ways to do this, some of the philosophies that go into it, and more.


When deploying your smart contracts on-chain, we all know that they are immutable.

But what if I told you… they are mutable?

Well, I wouldn’t really be correct. However, in a way, smart contracts “change” all the time. When people transfer tokens, when people stake in…

Using Brownie, Python, and Solidity, create a token that can be viewed, bought, and sold on the blockchain

Product logos as tokens
Photo by the author.

The Ethereum and blockchain ecosystem as a whole do commerce by using tokens. Anyone can create a token and use it as a cryptocurrency. We are going to be deploying an ERC20 token using Python, , and in this tutorial. You don’t need to be that familiar with any of these for this tutorial.

What Is an ERC20? What Is an Ethereum Token?

ERC20 means “Ethereum Request for Comment 20.” is a way for social groups to have ideas peer-reviewed. Ethereum makes improvements to the ecosystem by having people create ideas and having others comment on them. These are slightly different from

Using Aave flash loans is a great way to maximize your arbitrage. If your function doesn’t make money, it doesn’t execute, all you have to worry about is other bots beating you to the punch… Which does happen pretty often.

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When I first got started in crypto, I was but a wee quantitative engineer wannabe. I was enamored by the brilliance of the research engineers at the hedge fund I worked at, and wanted to try out some strategies.

Crypto seemed cool, and I met some people who knew a thing or two, and I started learning that you could buy an asset on one exchange, and if another exchange had a “bad” price, you could sell it there and make a profit.

My mind was blown, and I was like “Wow we found the money printer”. I later learned…

Using aiohttp, asyncio, event loops, and anything else to get our fintech data quicker

Python logo over purple backdrop
Original image by monsitj from Getty Images Pro.

The other day, I tried to download 16 million colors from an API I found online. My original thought was “Sure, I can do this with the requests library. It probably won’t take that long.”

Eight hours later, I was about 0.5% of the way through, so I decided it was time to refactor for the code to be asynchronous. It was also time to help anyone else along the way. …

We use Solidity, Brownie, Polygon/Matic, Chainlink VRF, Chainlink Data Feeds, and Chainlink external adapters to connect our smart contract to the real world… by ordering a random pizza

Order a pizza with a smart contract
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Huge shoutout to for helping with the front end.


are amazing advancements in the world today, and allow us to create worlds where trust isn’t an issue. However, about 90% of barely venture outside the blockchain to make meaningful impacts in our lives today. We care about technology only so far as to how much it helps us. If technology doesn’t improve my day today, I don’t really care about it.

However, blockchains have the power to impact and interact with the world outside the blockchain using . Oracles are the key to unlocking the…

A glorious guide to building and creating NFTs, the ERC-721 standard for creating collectibles, art, and any type of unique asset on-chain.

Letter keys
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(Non-Fungible Tokens) are the hot new up-and-comers in the smart contract space. If 2020 was the year of DeFi, then at least the start of 2021 belongs to NFTs. NFTs are a token standard similar to the .

A Non-Fungible Token means that it’s a unique token that has no other token like it. This is starkly different from the ERC20s, which are fungible. Fungible means “replaceable” or “interchangeable.” For example, your dollar bill is going to be worth $1 no matter what dollar bill you use. …

Ex-Hedge Fund Engineer explains how GME and WallStreetBets exemplify the exacerbated fintech industry and the outdated rails they run on. The 2008 crash, 2010 Flash Boys Revolt, and now the 2021 RobinHood/Reddit/GME uprising all point to one clear conclusion — the game is rigged. We either grow or risk repeating this forever

Robinhood, GME, ETH, and what’s next
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Our quality of life is as good as the rails that life runs on. Each aspect of our lives has its own infrastructure. Our communication runs on the internet. Our transportation runs on roads. Each year new technologies enter the market and usher in a new era of heightened prosperity in the area it affects.

When was the last time our monetary and market system got an upgrade? Some will argue that was when we got off the . In any case, we are at least 50 years outdated for an upgrade to how our monetary system and marketplace…

Why are smart contracts so important? What do smart contracts do? Why are smart contracts one of the most important technologies of the 2020s? How can smart contracts make our lives better? All these are answered and more.

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are the technology that will define how we humans interact in our future, and they’ve already started their explosive growth and adoption. We’ve seen smart contracts use in just the financial space alone go from , and projects that use smart contracts platforms have seen skyrocketing prices, like ETH going from $130 at the start of 2020, to .

Smart Contracts are enabled due to the technology known as . Blockchain is much more than just the flagship currency “bitcoin”. Bitcoin was the original blockchain use case, but there is more to…

Patrick Collins

Chainlink developer advocate, fintech data engineer, and human performance buff. . 🔵⛓🐸🥑

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