John R. Kosinski
Verified Expert in Engineering
Full-stack Developer
Chiang Mai, Thailand
Toptal member since February 9, 2016
As a veteran full-stack developer, John's great breadth and depth of experience include cryptocurrency, IoT, blockchain, and mobile projects. His foundation is in C and C++, with many years of experience in .NET. His work experience up until 2009 was in the NYC and NYC area. Since 2009, he's been living abroad and working remotely. John has a personal research project in the background, involving blockchain and deep neural networks.
Portfolio
Experience
- Software Development - 20 years
- .NET - 16 years
- C++ - 16 years
- Design Patterns - 14 years
- Technical Leadership - 7 years
- Banking & Finance - 5 years
- TypeScript - 4 years
- Solidity - 4 years
Availability
Preferred Environment
Ethers.js, Visual Studio, Visual Studio Code (VS Code), Scrum, Agile, Test-driven Development (TDD)
The most amazing...
...thing I've done recently was to develop a blockchain financial instrument that was one of the first of its kind.
Work Experience
CTO
Hamza Labs
- Developed Zeppelin, a network of smart contracts to track eCommerce sales affiliate activity on the blockchain.
- Architected and managed a team of developers to create and maintain a custom Medusa eCommerce multi-vendor website with a wallet authentication system.
- Architected and developed escrow smart contracts to support sales on the eCommerce website.
Software Developer
Leeds Rising
- Developed PyDAS: a robust, complete and well-tested Python API to the DAS trading platform API for buying, selling, borrowing, and short-selling US stocks.
- Developed and rigorously tested an algorithmic trading system using the PyDAS API, which can specify dynamic trading strategies, including a configurable Trigger and configurable plug-and-playable Trade logic.
- Implemented strategies for borrowing and short-selling illiquid stocks on the Nasdaq and NYSE. Deployed and tested those strategies on the live market.
DeFi Architect
Patagon Management LLC
- Architected and developed a dApp, one of the first of its kind, that allows users to buy into a US Treasury Bond fund on the blockchain. Launched on BSC and Ethereum blockchains. Won the race to market before competitors.
- Architected and developed a secure off-chain system to automate vault sweeps and other processes related to the Treasury Bond vault systems.
- Conducted technical research to assess the feasibility of various potential automated hedge fund strategies in the blockchain space.
- Implemented rigorous testing and security for on-chain blockchain products.
- Directed testing and development of the React front end for decentralized applications and administrative decentralized interfaces.
Technical Consultant
AxiomSys
- Planned and estimated project packages for non-fungible and fungible token development, front-end minting and administration websites with React, and security audits of smart contracts.
- Researched, planned, and presented the integration of fungible and non-fungible tokens with the Unity game engine back end of a well-known online meeting venue.
- Contacted, vetted, and interviewed blockchain developers, laying the foundations for an elite international team of blockchain warriors.
- Developed, planned, and documented a methodology for security audits of smart contracts.
- Provided expert technical consultation during sales meetings.
Senior C# Web3 Developer
Garbles Labs
- Ported the TypeScript SDK to C#/.NET for the well-known Solana market maker Orca Whirlpools to be used in the Unity game engine; made it open for community use.
- Developed the SDK for .NET, refactored as necessary, and added a suite of automated tests to ensure quality.
- Interfaced with the Rust smart contracts and modified the Rust code as needed for testability.
Enterprise C++ Developer
Alteryx
- Resolved customer and in-house defects in the software's main back-end C++ engine, using C++ 11 on both Windows and Linux platforms.
- Developed new features for the software's main back-end C++ engine, using C++ 11 on both Windows and Linux platforms as part of a team of developers.
- Fixed some of the most long-standing and challenging defects in the software; thoroughly documented the root causes and implemented testing to prevent a recurrence.
- Managed the defect lifecycle, interfacing with other teams for information and assistance when needed.
IoT Engineer
Jaber Medical
- Developed ESP8266 and ESP32 hardware prototypes for a unique and proprietary hospital emergency room communications system. The prototype included IR, WiFi, and an RFID chip scanner.
- Architected and developed embedded networked software for the ESP32/ESP8266 for the hardware prototype, with Arduino and RTOS in C, interacting with WiFi, IR, and RFID readers.
- Researched and made decisions and tradeoffs regarding software and hardware requirements, working closely with the client to meet their needs.
Alexa Developer
Anguleris Technologies
- Developed a rich Alexa app that will allow customers to run spoken English queries against a complex product database.
- Architected and developed the back end using DynamoDB on AWS, Node.js, and AWS SDK, to automate back-end data imports from providers and synchronize with the database.
- Developed a rigorous automated testing suite to ensure continued quality.
Alexa Developer
Sterling VC
- Developed and brought to market an Alexa skill for retrieving New York sporting news updates for Alexa Echo, Dot, and Show.
- Used DynamoDB, AWS Lambda scripts in Node.js, and AWS SDK to architect a back-end system for retrieving data from providers and keeping the database synchronized.
- Architected and implemented voice-activated UI for Alexa, as well as a visual UI for Alexa Show.
R&D Manager
Futronix
- Researched and directed research in the development of Alexa Skills for Amazon Echo Dot and how they could be integrated into existing company products.
- Researched possibilities of replacing the usage of proprietary chips in some of the company's existing products with less-expensive ESP8266 and ESP32 chips.
- Created a prototype module for integrating voice commands into the interfaces of an existing home lighting product, utilizing AWS and Alexa APIs.
- Presented and documented research findings, as well as new proposals for technological product improvements.
Automated Trade Analyst
Event Driven Investor
- Improved algorithms for analyzing the correlation between distinct financial asset price series.
- Corrected Pearson's coefficient calculations to discover the correlation between stock trading pairs.
- Refactored the C# application code for better organization, extensibility, and modularity.
- Added automated tests to discover bugs in the existing codebase. Analyzed and fixed the bugs found.
Node.js Developer
Private Client
- Developed a full and profitable algorithmic trading system to exploit arbitrage opportunities between cryptocurrency futures and spot markets.
- Tested and debugged the system, using APIs for various exchanges.
- Developed plugins to allow the system to be used on various popular crypto futures and spot exchanges.
Freelance Senior Xamarin Developer
Aquamonix
- Developed from scratch a Xamarin iOS application that controls large-scale SCADA irrigation systems via a Java middle tier.
- Built the MVP's architecture and prepared a plan to facilitate cross-platform ports.
- Created a tight system of synchronizing long-running tasks with the server side across multiple connections or app sessions.
Mobile Developer (Remote)
Door3/FreshDirect
- Developed a Webby-winning eCommerce iPad application using Xamarin.iOS to replace the company's legacy Objective-C application and to unify the Android and iOS legacy apps into a single codebase.
- Developed features for both the back and front end using Xamarin iOS, with a small team.
- Helped to architect the framework to combine the codebases of two legacy apps into one unified Xamarin app.
- Diagnosed and fixed defects in the company's legacy Android and iOS applications.
Senior Developer | Team Leader
Manao Software
- Managed a team of developers to produce a REST/JSON front end to a unique SAP-querying interface for EveryAngle.
- Designed the architecture for the above software using .NET Web API MVVM with NHibernate.
- Managed a team to develop the above software in .NET.
- Directed the QA unit testing using SoapUI; interfaced with the client's executive team.
Software Development Manager
HotelTravel.com
- Architected, oversaw, and wrote code (for some portions) for a full overhaul of the underlying back-end booking engine, a complex system for integrating data from various categories of hotel rate providers.
- Designed and implemented test-driven policies for automated and manual testing of new software components to ensure the quality of each component's development and the correctness of its implementation into the overall system.
- Mentored individual developers in software micro-design (e.g., design patterns), new technologies (such as mobile), and best practices for efficiency, security, and scalability.
Senior Developer
Morgan Stanley (NYC)
- Developed back-end logic for a new fixed-income product interface for Morgan Stanley's Global Wealth Management Platform.
- Designed and integrated .NET modules to interface with legacy mainframe systems written in COBOL.
- Pioneered test-driven development policies in the department, implementing rigorous automated tests for various projects.
Experience
Bond Vault for EVM Blockchains
https://streamprotocol.moneyPROJECT LINKS:
• streamprotocol.money
• appstreamprotocol.money/
• etherscan.io/address/0xd86FFB404147163e19E010a0e9d4995E0e36F335
• etherscan.io/address/0xADF789E61Bf38c463e4bA5B2B6E9C1Af6659e11b
https://etherscan.io/address/0xa0b86991c6218b36c1d19d4a2e9eb0ce3606eb48
• etherscan.io/address/0x746430119DA3EA0e398b93059e96F21bfabAa8a4
https://etherscan.io/address/0xD48425B7fb702F571D872f4b7046B30c9FA47e15
• bscscan.com/address/0x3daa26E70383B37E41434a8bF8e8bF3A335c144A
https://bscscan.com/address/0xB95Bc0d1057a43ACF608805c6D4e3e234e4d4C1b
• bscscan.com/address/0x8ac76a51cc950d9822d68b83fe1ad97b32cd580d
https://bscscan.com/address/0x2A7aD6908A08dD19D6c5090aA86E7c7E61C3e7F4
• bscscan.com/address/0x2900E387152a22370F482a0640701e1B41cc0896
• github.com/jrkosinski/evm-bond-vault
Zeppelin: EthGlobal 2023 Hackathon Winner
https://ethglobal.com/showcase/zeppelinfinance-gvawnCreated using Solidity, Hardhat, TypeScript, Tableland, and Next.js.
Common NFT Contract Design Anti-patterns
https://medium.com/@john.kosinski/4-common-nft-contract-design-anti-patterns-dd519c02a7afScanning the blockchain's verified NFTs, I frequently see recurring common anti-patterns. I wrote an article listing what I think are the most common ones, some thoughts about why they occur, and some better alternatives.
Security Manager Design Pattern in Solidity
https://medium.com/@john.kosinski/security-manager-design-pattern-in-solidity-d8851779cb6dEthernaut Solutions
https://github.com/jrkosinski/EthernautKrew NFT Project
https://github.com/jrkosinski/krewnime-nftFreshDirect iOS
Aquamonix iOS
https://apps.apple.com/nz/app/aquamonix/id1166491146IoT Demo for Alexa
https://github.com/jrkosinski/AlexaTvRemoteIt is associated with the Toptal blog article available at toptal.com/arduino/esp8266-arduino-tutorial-alexa-hack
Medium Articles
https://medium.com/@john.kosinski• blockchain development and architecture
• machine learning and AI
• statistics
• software development and architecture
• communication skills
Preparing and Shaping Timeseries Data for Keras LSTM Input
https://medium.com/@john.kosinski/preparing-and-shaping-timeseries-data-for-keras-lstm-input-part-one-5bb882bc2143The preprocessing described and demonstrated includes statistical transformations like scaling, handling outliers, removing the trend, and extracting important features. It also includes the correct way to shape the data into the appropriate number of dimensions.
The article is in two parts:
Part 1: https://medium.com/@john.kosinski/preparing-and-shaping-timeseries-data-for-keras-lstm-input-part-one-5bb882bc2143
Part 2: https://medium.com/@john.kosinski/preparing-and-shaping-timeseries-data-for-keras-lstm-input-part-two-ad17f6ab450
Education
Bachelor of Science in Computer Science
University of Delaware - Newark, DE, USA
Certifications
AWS Certified Solutions Architect – Associate
Amazon Web Services
Blockchain Platforms
University at Buffalo & The State University of New York | via Coursera
Decentralized Applications (Dapps)
University at Buffalo & The State University of New York | via Coursera
Smart Contracts
University at Buffalo & The State University of New York | via Coursera
Blockchain Basics
University at Buffalo & The State University of New York | via Coursera
MCT (Microsoft Certified Trainer)
Microsoft
MCSD (Microsoft Certified Solutions Developer)
Microsoft
Skills
Libraries/APIs
Node.js, Web3.js, Amazon API, REST APIs, Interactive Brokers API, Xamarin.Android, Xamarin.iOS, Mailchimp API, Mixpanel API, TensorFlow, React, Binance API, Keras, TensorFlow Deep Learning Library (TFLearn), Infragistics, LSTM
Tools
Microsoft Visual Studio, NPM, Jira, MetaMask, Git, Amazon Simple Notification Service (SNS), Perforce, Mongoose, Amazon Simple Email Service (SES), MQTT, SoapUI, Visual Studio, Confluence, Amazon Simple Queue Service (SQS), Crystal Reports
Languages
Solidity, C#, JavaScript, C++, C#.NET, Python, C, Assembly, SQL, TypeScript, C++11, Rust, HTML, Embedded C++, Go, Java, Perl, PHP, Haskell, GraphQL, Solidity Assembly
Frameworks
.NET, ASP.NET Core, .NET 4, .NET Core, ASP.NET MVC, ASP.NET, Express.js, Knockout (Knockout.js), React Native, Unity, Next.js
Paradigms
RESTful Development, Agile Software Development, Scrum, REST, Design Patterns, Application Architecture, Model View ViewModel (MVVM), Model View Controller (MVC), Kanban, Unit Testing, Microservices, Windows App Development, Object-relational Mapping (ORM), Mobile Development, Test-driven Development (TDD), Service-oriented Architecture (SOA), Functional Programming, Agile, Penetration Testing, Serverless Architecture
Platforms
Blockchain, Ethereum, Magento, Amazon Web Services (AWS), Blockchain Platforms, Linux, Arduino, Amazon Alexa, Android, iOS, Web, Xamarin, Unix, Windows, Amazon EC2, AWS Lambda, AWS IoT, Docker, Visual Studio Code (VS Code), Jupyter Notebook, Azure, Mobile, Twilio, Medusa
Storage
JSON, Microsoft SQL Server, MySQL, PostgreSQL, Amazon DynamoDB, NoSQL, MongoDB
Industry Expertise
Banking & Finance, Trading Systems
Other
Ethereum Smart Contracts, Software Development, Software Architecture, Complex Problem Solving, Computer Science, Full-stack, Crypto, Architecture, Web 3.0, Back-end, Technical Architecture, Solution Architecture, Smart Contracts, SOAP, WebSockets, ESP8266, Internet of Things (IoT), HTTP, eCommerce, Trading, ESP32, Leadership, Technical Leadership, Team Leadership, Lean Project Management, Solana, Non-fungible Tokens (NFT), Token Design, Ethers.js, Decentralized Finance (DeFi), APIs, Blockchain & Cryptocurrency, Cryptocurrency, Algorithms, Rinkeby, Algorithmic Trading, Algorithmic Trading Analysis, IIS, Legacy Software, Windows Services, API Integration, Automated Trading Software, Stock Trading, Stock Analysis, Prediction Markets, Visualization, Data Engineering, Mobile Apps, Decentralized Systems, ERC-20, Fintech, Multithreading, Web Development, Lambda Functions, Enterprise Architecture, User Interface (UI), Domain-driven Design (DDD), RESTful Services, Internet Server Application Programming Interface (ISAPI), COM, Embedded Systems, Real-time Operating System (RTOS), Customized Blockchains, Machine Learning, Defect Management, Arbitrage, Futures, Software, CI/CD Pipelines, OpenSea, Bots, DApps, Integration, Amazon RDS, Training, Web Security, Deep Learning, Hedge Funds, Finance, Statistics, Long Short-term Memory (LSTM), Neural Networks, Recurrent Neural Networks (RNNs), Gaming, R&D, Presentations, Web3, Move, Bitcoin, Cloud, WinDev
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