John is available for hire
Hire JohnJohn McLaughlin
Verified Expert in Engineering
Blockchain Developer
New York, NY, United States
Toptal member since September 12, 2022
Bio
John is an experienced Ethereum dApp developer. He has created NFT factories and marketplaces on Ethereum Mainnet and L2 chains like Polygon, Arbitrum, Optimism, and zkSync for five Toptal clients. He has designed and deployed 150 unique Solidity smart contracts (ERC-20, ERC-721, ERC-1155) integrated into various decentralized platforms and applications. As an AWS Certified Developer Associate, John has also developed and deployed serverless applications for Toptal and other freelance clients.
Portfolio
Lucas Flett
Blockchain, Python, Decentralized Finance (DeFi), Solana, Solana.py, Rust
Mueller Health Foundation, Inc
Blockchain, Ethereum Smart Contracts, React, Node.js, Full-stack, JavaScript...
Polemarch LLC
Blockchain, Web 3.0, Smart Contracts, Node.js, Python, Security, IT Security...
Experience
Availability
Part-time
Preferred Environment
React, Next.js, Solidity, Web3, Ethers.js, Hardhat, IPFS, Docker, Ethereum Virtual Machine (EVM), Amazon Web Services (AWS)
The most amazing...
...application I've developed is an NFT factory/marketplace for the April 2022 ETHGlobal DAOHacks hackathon. The marketplace won prizes.
Work Experience
Python Developer (via Toptal)
2024 - 2024
Lucas Flett
- Designed and developed a Python-based trading bot connector for decentralized and centralized cryptocurrency exchanges, optimizing execution speed and transaction efficiency.
- Created a custom Telegram UI that allowed users to start trading bot scripts, submit algorithm-based orders, and monitor execution status directly within the exchange account UI.
- Conducted detailed code reviews for team members by evaluating GitHub pull requests, ensuring code quality and alignment with project standards before repository updates.
- Researched and analyzed 3rd-party asset custody solutions to determine optimal integration strategies for enhanced platform security and compliance.
Technologies: Blockchain, Python, Decentralized Finance (DeFi), Solana, Solana.py, Rust
Full-stack Blockchain Developer
2023 - 2024
Mueller Health Foundation, Inc
- Developed minting of on-chain NFTs to represent documents stored on the TBConnect app related to tuberculosis research and analysis.
- Upgraded overall application from Node.js 8 to Node.js 16 and React 16 to React 17 in 2023. Upgraded dependencies and cleared all errors to improve overall performance.
- Deployed the upgraded back-end to an AWS EC2 instance, the front-end to an AWS S3 bucket, and various APIs to Amazon API Gateway. As a result, the application is now fast, scalable with resizable compute capacity, highly secure, and very efficient.
- Upgraded the chat and virtual meeting functionality from Twilio Video to the Zoom Video SDK to enable group meetings instead of one-to-one sessions.
- Updated the visual aesthetic of the front end to enhance the overall user experience, making it more intuitive, engaging, and visually appealing.
Technologies: Blockchain, Ethereum Smart Contracts, React, Node.js, Full-stack, JavaScript, Ethereum, Amazon Web Services (AWS), Twilio, Blockchain, Zoom, AWS Cloud Computing Services, Use Case Analysis, Ganache
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, Project Consultancy, Use Case Analysis, Binance Cryptocurrency Exchange
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, Project Consultancy, Use Case Analysis, zkSync, Decentralized Finance (DeFi), Binance Cryptocurrency Exchange
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, Project Consultancy, Use Case Analysis, Ganache, Binance Cryptocurrency Exchange
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, Project Consultancy, Arbitrage, Use Case Analysis, Ganache
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, Azure, Project Consultancy, Twilio API, Arbitrage, Use Case Analysis, Arbitrum, zkSync, Ganache, Decentralized Finance (DeFi), Binance Cryptocurrency Exchange
Adjunct Lecturer
2011 - 2022
CUNY-College of Staten Island
- Instructed on personal finance, using accounting software such as Microsoft 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 Development, 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, Project Consultancy
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 due to 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 possibly making a manual connection to the Metamask Goerli wallet (update shortly). If you need Goerli testnet tokens to test the app, please email 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.
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
JUNE 2024 - JUNE 2027
AWS Certified Developer – Associate
Amazon Web Services
JULY 2023 - PRESENT
AWS Partner: Accreditation (Technical)
Amazon Web Services Training and Certification
DECEMBER 2021 - PRESENT
ConsenSys Certified Ethereum Developer
ConsenSys Academy
SEPTEMBER 2020 - PRESENT
LFS171x: Introduction to Hyperledger Blockchain Technologies
The Linux Foundation | via edX
JUNE 2020 - PRESENT
The Python Mega Course: Build Ten Real World Apps
Udemy
SEPTEMBER 2019 - PRESENT
Modern React with Redux
Udemy
AUGUST 2019 - PRESENT
Codecademy Intensive Program: Build Front-end Web Apps from Scratch
Codecademy
FEBRUARY 2019 - PRESENT
Docker Mastery: The Complete Toolset From a Docker Captain
Udemy
Skills
Libraries/APIs
React, Node.js, Web3.js, Twilio API, OpenZeppelin, Solana.py, React Redux
Tools
Microsoft Excel, MetaMask, Excel 2010, Git, GitHub, Ganache, Docker Compose, Docker Swarm, Docker Hub, Zoom, MATLAB, Excel 2013
Languages
Solidity, JavaScript, HTML, CSS, HTML5, Python, TypeScript, Python 3, Python 2, Rust, Markdown
Frameworks
Next.js, Truffle, Hardhat, Flask, Redux
Paradigms
DevOps, Microservices Architecture, Distributed Computing
Platforms
Docker, Linux, Ethereum, Hyperledger, Windows, Blockchain, Decentralized Exchanges (DEXs), Blockchain Platforms, Amazon Web Services (AWS), DigitalOcean, AWS Cloud Computing Services, Hyperledger Fabric, Netlify, Twilio, Azure, Vercel, Kubernetes
Storage
Databases, PostgreSQL, MySQL, Docker Cloud, Redis
Industry Expertise
Binance Cryptocurrency Exchange, Cybersecurity
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 Development, Technical Writing, Smart Contracts, Blockchain & Cryptocurrency, Full-stack, ERC-20, Multisig, Blockchain, Decentralized Autonomous Organizations (DAO), zkSync, 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, AWS Partner Network (APN), APIs, 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, Project Consultancy, Arbitrage, Use Case Analysis, IPFS, CSS5, Arbitrum, Govtech, Mobile Advertising, Blockchain as a Service, GPU Computing, Filecoin, Intuit QuickBooks, K-12 Education, Business, Mathematical Finance, Personal Finance, Excel 365
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