John is available for hire

John McLaughlin

Verified Expert in Engineering

Blockchain Developer

Location

New York, NY, United States

Toptal Member Since

September 12, 2022

John has professional experience developing Ethereum decentralized apps (dApps), including an NFT factory and marketplace deployed on Mainnet and L2 chains such as Polygon, Arbitrum, Optimism, and zkSync. He has created two video/audio storage apps using IPFS/Filecoin and designed and deployed a Hyperledger Fabric permissioned blockchain to organize McKurz Capital's financials. John has also designed container orchestrations using Docker and Kubernetes for various web2 and web3 apps.

Portfolio

Polemarch LLC

Blockchain, Web 3.0, Smart Contracts, Node.js, Python, Security, IT Security...

Levi Sirmons

JavaScript, Blockchain, MetaMask, Advisory, Strategy, Troubleshooting...

Currentz Corp.

Solidity, JavaScript, Ethereum, Smart Contracts, Blockchain, React, MetaMask...

Experience

Docker - 5 years Git - 5 years Solidity - 4 years Ethereum Smart Contracts - 4 years Truffle - 4 years Web3 - 4 years Hardhat - 3 years Next.js - 3 years

Availability

Part-time

Preferred Environment

React, Next.js, Solidity, Web3, Ethers.js, Truffle, Hardhat, Markdown, IPFS, Docker, Ethereum Virtual Machine (EVM)

The most amazing...

...application I've developed is an NFT factory/marketplace for the April 2022 ETHGlobal DAOHacks hackathon, which won prizes.

Work Experience

Web3 Back-end Developer

2023 - 2023

Polemarch LLC

Developed an Ethereum NFT marketplace for listing Bitcoin ordinal inscriptions with full function to create, mint, and list EVM NFTs representing inscribed Bitcoin ordinals, BRC-20 tokens, and name inscriptions.
Contributed to the smart contract Solidity smart contract behind the NFT marketplace featured createNFT, listNFT, cancelListing, addToCart, burn, and other relevant functions.
Worked on the contract design that utilized OpenZeppelin audited contract library to ensure safety and security.
Designed and developed a REST API for storing Bitcoin inscription off-chain data such as collection value, curation, real-time pricing of listed NFTs in terms of ETH/USD, etc. The API utilized MongoDB for storage.

Technologies: Blockchain, Web 3.0, Smart Contracts, Node.js, Python, Security, IT Security, APIs, Bitcoin, Ethereum, Data Queries, Databases, DevOps, Ethereum Virtual Machine (EVM), Software Architecture, DApps, Microservices Architecture, Cryptography, Computer Science, White Papers, Distributed Computing

Blockchain Developer

2023 - 2023

Levi Sirmons

Developed an Ethereum wallet that removed and added specific functionalities to the basic Metamask web3 wallet.
Added permissions to the web3 wallet where it can be used by team members who do not possess administrative rights and permissions to the firm's treasury wallet(s).
Created a web3 wallet browser extension distribution that can be uploaded into Chrome, Firefox, or Brave.
Assisted in designing a team workflow that allows for close supervision of trading strategies by platform administrators.

Technologies: JavaScript, Blockchain, MetaMask, Advisory, Strategy, Troubleshooting, TypeScript, Data Queries, Databases, Writing & Editing, Ethereum Virtual Machine (EVM), Software Architecture, Computer Science

Blockchain Developer

2022 - 2023

Currentz Corp.

Worked as the lead blockchain developer for Currentz. Designed, developed, and deployed ER-C721 and ERC-1155 Solidity smart contracts for the Ethereum and EVM-compatible blockchains.
Created a defined process for the team to set up NFT drops with a user interface for customers to mint and claim NFTs from their creative economy platform.
Integrated not only Web 3.0 payments using cryptocurrencies through a Metamask wallet but also purchasing the NFTs using a credit card where customer knowledge of Web 3.0 is not necessary.
Deployed contracts on Layer 2 chains such as Polygon or Optimism to allow the platform and its customers to save transaction "gas fees" when using cryptocurrencies.

Technologies: Solidity, JavaScript, Ethereum, Smart Contracts, Blockchain, React, MetaMask, Non-fungible Tokens (NFT), Blockchain & Cryptocurrency, Blockchain Platforms, Crypto, Security, IT Security, Technical Writing, Advisory, Blockchain as a Service, Strategy, Back-end Development, Web Development, Troubleshooting, TypeScript, Writing & Editing, Decentralized Autonomous Organizations (DAO), Ethereum Virtual Machine (EVM), Tokenomics, Software Architecture, DApps, Computer Science, Solana

Senior Blockchain Developer

2022 - 2022

John Nesgoda - Web3 Startup

Developed an Ethereum Solidity smart contract with tokenomics functionalities.
Implemented multi-signature wallet functionality as a method of custody.
Added payment streaming functionality to multi-signature wallet orchestration.
Designed and deployed a platform membership NFT token with an expiration date and the functionality to extend the expiration date.

Technologies: Blockchain & Cryptocurrency, Solidity, Decentralized Finance (DeFi), Ethereum Smart Contracts, Multisig, MetaMask, CTO, Electronic Payments, Fraud Prevention, Cryptocurrency Wallets, Payment APIs, Fintech, Branding, Cryptocurrency, Decentralized Systems, Web 3.0, Fintech Consultant, Foundry, Next.js, Ethers.js, GitHub, Node.js, Polygon, Crypto, Security, IT Security, JavaScript, Blockchain, Technical Writing, Advisory, Back-end Development, Web Development, Troubleshooting, TypeScript, Data Queries, Writing & Editing, Ethereum Virtual Machine (EVM), Tokenomics, Software Architecture, DApps, Computer Science, White Papers

Lead Blockchain Developer

2017 - 2022

McKurz Capital Incorporated

Founded McKurz as a part-time development shop for Web3 applications, submitting our apps to 11 ETHGlobal and two Chainlink hackathons. Several of these apps won prizes in hackathon competitions and the interest of venture capital firms.
Built Ethereum smart contract web apps using development tools such as Truffle and Hardhat, with React and Next.js as front ends.
Deployed an NFT factory/marketplace to the Polygon blockchain during the ETHGlobal DAOHacks hackathon.
Developed a few storage apps deployed to the Filecoin blockchain that were submitted to hackathons last year, including Disco Rock Repo for the 1960s to 1990s disco, rock, and pop music and Fin File Crypto for crypto investment videos and documents.

Technologies: Solidity, Ethereum, Truffle, Hardhat, Node.js, React, Docker, Blockchain, Smart Contracts, Blockchain & Cryptocurrency, Decentralized Exchanges (DEXs), Full-stack, ERC-20, HTML5, CSS5, Web3.js, OpenSea, Bitcoin, CTO, Electronic Payments, Fraud Prevention, Cryptocurrency Wallets, Govtech, Payment APIs, Fintech, Branding, Cryptocurrency, Rust, Amazon Web Services (AWS), Decentralized Systems, Mobile Advertising, Web 3.0, Fintech Consultant, Hyperledger Fabric, Hyperledger, Kubernetes, Foundry, Netlify, Next.js, Ethers.js, GitHub, Polygon, Python, Cloud, Crypto, Cybersecurity, Twilio, Security, IT Security, MetaMask, JavaScript, DigitalOcean, Technical Writing, Advisory, Blockchain as a Service, Strategy, Back-end Development, Web Development, APIs, Troubleshooting, TypeScript, DevOps, Data Queries, Databases, PostgreSQL, Redis, Writing & Editing, Ethereum Virtual Machine (EVM), Tokenomics, Software Architecture, Technical Leadership, Leadership, DApps, Microservices Architecture, Cryptography, Computer Science, White Papers, Distributed Computing, GPU Computing, Solana

Adjunct Lecturer

2011 - 2022

CUNY-College of Staten Island

Instructed on personal finance, using accounting software such as MS Excel and QuickBooks.
Led students on financial topics through a technology lens to better equip them for the 21st-century digital economy.
Lectured on the history of blockchain, industry trends, and investing analysis into various projects such as Bitcoin, Ethereum, Solana, decentralized finance protocols, and NFTs.

Technologies: Windows, Google Drive, Excel 2010, Intuit QuickBooks, Bitcoin, Fraud Prevention, Cryptocurrency Wallets, Govtech, Fintech, Branding, Cryptocurrency, Decentralized Systems, Web 3.0, Crypto, Cybersecurity, Blockchain, Troubleshooting, Writing & Editing, Leadership

Teacher

2005 - 2022

New York City Department of Education

Taught mathematics topics such as basic algebra, intermediate algebra and trigonometry, and logic and pre-calculus.
Instructed entrepreneurship students about website development using HTML, CSS, and JavaScript.
Expanded student knowledge to extend JavaScript development to Node.js, React, and Next.js, with additional topics toward server-based development.
Introduced students to blockchain history and use cases, the theory on Ethereum smart contracts, and the potential of cryptocurrency-based applications.

Technologies: K-12 Education, Business, Mathematical Finance, Technical Writing, Personal Finance, Excel 2013, Excel 365, Intuit QuickBooks, JavaScript, HTML, CSS, Bitcoin, Cryptocurrency Wallets, Govtech, Branding, Node.js, Writing & Editing

Experience

Nature NFTs Marketplace

https://nature-nfts-marketplace-polygon.vercel.app/

The Nature NFT Marketplace is an NFT factory deployed on the Polygon Mainnet blockchain. It allows users to create their own NFT from a digital image, list it for sale on the marketplace, and actively trade all users' NFT listings. It was built with an Ethereum smart contract that adds the previously mentioned functionality. I have deployed the app to the Polygon and Arbitrum blockchains in an effort to lower transaction "gas" fees. This project's GitHub repository can be found at: github.com/georgemac510/nature-nfts-marketplace-polygon.

Legal Documents Marketplace

https://legaldoc.surge.sh/

The Legal Documents form repository is a datastore and marketplace for purchasing common fillable-PDF legal documents such as a simple will, articles of incorporation for specific states or provinces, bill of sale samples, building contracts, and business plans. Currently, the legal documents are stored as .jpg files. In future iterations, the documents will be fileable-PDFs so users can fill them with their unique information and use them for their purposes. The legal documents are stored on IPFS and deployed to the Goerli Ethereum Testnet as ERC-721 NFTs. This project's GitHub repository can be found at: github.com/georgemac510/blockchain-developer-bootcamp-final-project. Your Metamask account must be set to the Goerli blockchain to view and interact with the app.

Decentralized Token Exchange

https://mckurz-dex.vercel.app/

The McKurz cryptocurrency exchange dApp was launched on the Ethereum Kovan Test Network in August 2020. It has since been upgraded to the Goerli testnet as a result of the Ethereum Merge and the deprecation of the Kovan chain. The exchange allows users to list buy and sell orders of different cryptocurrencies. The app is an older production and works best with unlocking Metamask with your password, refreshing the browser after connection, and a possible manual connection to the Metamask Goerli wallet (update shortly). If you are in need of Goerli testnet tokens to test the app, please send an email to john.mclaughlin@toptal.com with your Goerli Ethereum address, and testnet tokens will be sent to your address.

Safe Harbour Finance Reward Coin Staking App Deployed to zkSync

https://safeharbour-finance.vercel.app/

The Safe Harbour Finance app allows users to stake native SAFE tokens and acquire rewards of the platform's native SAFE token. The app's uniqueness is that it is deployed to the zkSync testnet 2.0, where costs of staking, transfer, lending, or borrowing are quite inexpensive and secure. To use the app, you will need to add the 'zkSync alpha testnet' to Metamask. Directions for this process can be found at: https://v2-docs.zksync.io/dev/troubleshooting/important-links.html#testnet-network-info. Demonstrations of the app are available.

Skills

Languages

Solidity, JavaScript, HTML, CSS, HTML5, Python, TypeScript, Python 3, Python 2, Markdown, Rust

Frameworks

Next.js, Truffle, Hardhat, Flask, Redux

Libraries/APIs

React, Node.js, Web3.js, OpenZeppelin, React Redux

Tools

Microsoft Excel, MetaMask, Excel 2010, Git, GitHub, Docker Compose, Docker Swarm, Docker Hub, MATLAB, Excel 2013

Paradigms

DevOps, Microservices Architecture, Distributed Computing

Platforms

Docker, Linux, Ethereum, Hyperledger, Windows, Blockchain, Blockchain Platforms, DigitalOcean, Hyperledger Fabric, Amazon Web Services (AWS), Netlify, Twilio, Vercel, Kubernetes, AWS Cloud Computing Services

Storage

Databases, PostgreSQL, MySQL, Docker Cloud, Redis

Other

Web3, Ethers.js, Distributed Team Management, Instruction & Coaching, Time Management, Infura, Non-fungible Tokens (NFT), Decentralized Finance (DeFi), Ethereum Smart Contracts, Ethereum Test Network, Google Drive, Technical Writing, Smart Contracts, Blockchain & Cryptocurrency, Decentralized Exchanges (DEXs), Full-stack, ERC-20, Multisig, Blockchain Design, Decentralized Autonomous Organizations (DAO), OpenSea, Bitcoin, CTO, Electronic Payments, Fraud Prevention, Cryptocurrency Wallets, Payment APIs, Fintech, Branding, Cryptocurrency, Decentralized Systems, Web 3.0, Fintech Consultant, Foundry, Polygon, Cloud, Crypto, Security, IT Security, Advisory, Strategy, Back-end Development, Web Development, Troubleshooting, Data Queries, Writing & Editing, Pulse Width Modulation (PWM), Ethereum Virtual Machine (EVM), Tokenomics, Software Architecture, Technical Leadership, Leadership, DApps, Cryptography, Computer Science, White Papers, Solana, IPFS, CSS5, Arbitrum, zkSync, Govtech, Mobile Advertising, Blockchain as a Service, APIs, GPU Computing, Filecoin, Intuit QuickBooks, K-12 Education, Business, Mathematical Finance, Personal Finance, Excel 365, AWS Partner Network (APN)

Industry Expertise

Cybersecurity

Education

2014 - 2016

Master's Degree in Education Administration

City University of New York (CUNY) - Hunter College - New York City, New York, United States

2005 - 2009

Master's Degree in Mathematics Education

City University of New York (CUNY)-Brooklyn College - New York City, New York, United States

1983 - 2005

Bachelor's Degree in Accounting, Business Management, and English

St. John's University - New York City, New York, United States

Certifications

JULY 2023 - PRESENT

AWS Partner: Accreditation (Technical)

Amazon Web Services Training and Certification

DECEMBER 2021 - PRESENT

ConsenSys Certified Ethereum Developer | courses.consensys.net/certificates/nywvhuwfkt

ConsenSys Academy

SEPTEMBER 2020 - PRESENT

Hyperledger Blockchain Technologies | courses.edx.org/certificates/900e628fce4743c8b17b73c4372bc562

The Linux Foundation | via edX

JUNE 2020 - PRESENT

The Python Mega Course: Build Ten Real World Apps | ude.my/UC-5d483724-79d7-481b-ab4e-c7738cfa9750/

Udemy

SEPTEMBER 2019 - PRESENT

Modern React with Redux | ude.my/UC-CGW77936

Udemy

AUGUST 2019 - PRESENT

Codecademy Intensive Program: Build Front-end Web Apps from Scratch | credential.net/6acs57hh

Codecademy

FEBRUARY 2019 - PRESENT

Docker Mastery: The Complete Toolset From a Docker Captain | ude.my/UC-S8K3EJQD

Udemy

Collaboration That Works

How to Work with Toptal

Toptal matches you directly with global industry experts from our network in hours—not weeks or months.

Share your needs

Discuss your requirements and refine your scope in a call with a Toptal domain expert.

Choose your talent

Get a short list of expertly matched talent within 24 hours to review, interview, and choose from.

Start your risk-free talent trial

Work with your chosen talent on a trial basis for up to two weeks. Pay only if you decide to hire them.

Top talent is in high demand.

Start hiring