John R. Kosinski, Software Developer in Chiang Mai, Thailand
John R. Kosinski

Software Developer in Chiang Mai, Thailand

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. He is currently finishing a brief hiatus to study Blockchain and smart contract development.
John is now available for hire

Portfolio

  • AxiomSys
    Solidity, Blockchain, Smart Contracts, Ethereum, Ethereum Smart Contracts...
  • Alteryx
    C#, .NET, Microsoft Visual Studio, C++11, C++, Test-driven Development (TDD)...
  • Jaber Medical
    Amazon Web Services (AWS), ESP32, ESP8266, Embedded Systems, Amazon DynamoDB...

Experience

Location

Chiang Mai, Thailand

Availability

Part-time

Preferred Environment

Ethers.js, Visual Studio, Visual Studio Code, Scrum, Agile, Test-driven Development (TDD)

The most amazing...

...thing I've done was develop Alexa Skills for Amazon Dot and Echo.

Employment

  • Technical Consultant

    2022 - PRESENT
    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 and planned 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 smart contract 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.
    Technologies: Solidity, Blockchain, Smart Contracts, Ethereum, Ethereum Smart Contracts, Solana, C#, JavaScript, .NET, Unity, Software Development, Blockchain & Cryptocurrency, Full-stack, Rust, Cryptocurrency, Unix, C#.NET, TypeScript, Crypto, Architecture, React, MetaMask, Rinkeby
  • Enterprise C++ Developer

    2019 - 2022
    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.
    • Managed the defect lifecycle, interfacing with other teams for information and assistance when needed.
    Technologies: C#, .NET, Microsoft Visual Studio, C++11, C++, Test-driven Development (TDD), Defect Management, Microsoft SQL Server, Agile Software Development, Unit Testing, Software Development, Design Patterns, Complex Problem Solving, Linux, JavaScript, APIs, CI/CD Pipelines, SQL, Unix, Integration, C#.NET, Architecture, Algorithms
  • IoT Engineer

    2018 - 2019
    Jaber Medical
    • Contributed to networked embedded development on IoT devices that were connected to a central server; not at liberty to discuss details at the moment.
    Technologies: Amazon Web Services (AWS), ESP32, ESP8266, Embedded Systems, Amazon DynamoDB, AWS, Arduino, C++, Internet of Things (IoT), C, JavaScript, Agile Software Development, Android Studio, Node.js, Unit Testing, AWS IoT, RTOS, MQTT, Software Development, Design Patterns, Embedded C++, Complex Problem Solving, Microservices, Linux, APIs, Full-stack, TypeScript, Architecture, AWS EC2, AWS Lambda
  • Alexa Developer

    2018 - 2018
    Anguleris Technologies
    • Developed a rich Alexa app that will allow customers to run spoken English queries against a complex product database.
    Technologies: Amazon Web Services (AWS), AWS, Amazon Alexa, JavaScript, Agile Software Development, Unit Testing, AWS IoT, Software Development, Design Patterns, Complex Problem Solving, AWS EC2, AWS Lambda, Amazon DynamoDB
  • Alexa Developer

    2017 - 2018
    Sterling VC
    • Developed and brought to market an Alexa skill for retrieving New York sporting news updates.
    Technologies: Amazon Web Services (AWS), AWS, Node.js, Amazon Alexa, Agile Software Development, Unit Testing, AWS IoT, Software Development, Design Patterns, Complex Problem Solving, JavaScript, Full-stack, AWS EC2, AWS Lambda, Amazon DynamoDB
  • R&D Manager

    2017 - 2018
    Futronix
    • Developed Alexa Skills for Amazon Dot/Echo.
    • Worked with ESP8266 embedded programming with Arduino IDE.
    • Configured a TLSv1.2 WebSocket security.
    • Developed MQTT communication with AWS IoT cloud.
    • Created a voice-activated smart-home lighting system.
    Technologies: Amazon Web Services (AWS), Amazon Alexa, Arduino, Embedded C++, ESP8266, AWS, Internet of Things (IoT), JavaScript, .NET, Agile Software Development, Android Studio, Node.js, Unit Testing, AWS IoT, RTOS, Embedded Systems, MQTT, ESP32, Software Development, Design Patterns, .NET Core, Complex Problem Solving, Linux, C#, Unix, Architecture, AWS EC2, AWS Lambda, Amazon DynamoDB
  • Node.js Developer

    2016 - 2017
    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.
    Technologies: Blockchain, Trading, Arbitrage, Futures, JavaScript, Agile Software Development, Node.js, Unit Testing, Software Development, Design Patterns, Complex Problem Solving, Docker, Linux, C#, .NET, Microsoft Visual Studio, Ethereum Smart Contracts, Decentralized Finance (DeFi), APIs, Arbitrage Trading Experience, Blockchain & Cryptocurrency, Full-stack, Bots, Binance API, Cryptocurrency, Unix, Integration, TypeScript, Crypto, Architecture, Rinkeby, AWS EC2, AWS RDS, AWS Lambda, Amazon DynamoDB
  • Freelance Senior Xamarin Developer

    2015 - 2017
    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.
    Technologies: WebSockets, C#, JavaScript, .NET, Microsoft Visual Studio, Agile Software Development, Android Studio, Xamarin.Forms, Node.js, Unit Testing, Software Development, Design Patterns, Xamarin.iOS, Complex Problem Solving, Full-stack, SQL, C#.NET, REST APIs
  • Mobile Developer (Remote)

    2014 - 2016
    Door3/FreshDirect
    • Developed a Webby-winning eCommerce iPad application using Xamarin iOS.
    • Added new features on a legacy Objective-C app.
    • Installed new features on a legacy Android app.
    • Consolidated the legacy apps into a new Xamarin unified platform.
    Technologies: Selendroid, Java, Objective-C, Scrum, Jira, Android, iOS, Xamarin, C#, JavaScript, Agile Software Development, Node.js, Android Studio, Xamarin.Forms, Unit Testing, eCommerce, Software Development, Model View Controller (MVC), Design Patterns, Model View Viewmodel (MVVM), Xamarin.iOS, Complex Problem Solving, .NET, APIs, Full-stack, SQL, Integration, C#.NET, Architecture, REST APIs
  • Senior Developer | Team Leader

    2012 - 2014
    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.
    Technologies: RESTful Services, Domain-driven Design (DDD), Perforce, Jira, Scrum, Test-driven Development (TDD), UI, SOAP, jQuery, Knockout (Knockout.js), Model View Viewmodel (MVVM), JSON, C#, Microsoft Visual Studio, Agile Software Development, Android Studio, ASP.NET, Unit Testing, WebSockets, Software Development, Model View Controller (MVC), Design Patterns, Xamarin.iOS, Leadership, Technical Leadership, Team Leadership, Lean Project Management, .NET Core, Complex Problem Solving, Microservices, C++, Linux, .NET, APIs, HTML, Unix, C#.NET, Architecture, Windows, ASP.NET MVC, REST APIs, AWS RDS
  • Software Development Manager

    2009 - 2012
    HotelTravel.com
    • Redesigned the rate providers' pulling subsystem.
    • Developed ISAPI filters for the website.
    • Built a prototype mobile/web app.
    • Handled the day-to-day process of development and quality control.
    • Managed a team of 16-20 developers.
    Technologies: Internet Server Application Programming Interface (ISAPI), Android, VB.NET, PHP, Microsoft SQL Server, C++, C#, Microsoft Visual Studio, Agile Software Development, ASP.NET, Unit Testing, WebSockets, Software Development, Design Patterns, ASP, Leadership, Technical Leadership, Team Leadership, Lean Project Management, Complex Problem Solving, Linux, .NET, HTML, SQL, C#.NET, Architecture, Windows App Development, Windows, ASP.NET MVC, REST APIs
  • Senior Developer

    2007 - 2009
    Morgan Stanley (NYC)
    • Performed the application and web service programming in C# and VB.NET.
    • Interfaced .NET software with legacy COBOL programs.
    • Wrote the GUI design/programming in ASP.NET and JavaScript.
    • Developed software to manage fixed income securities based on currency exchange models.
    • Designed service-based architecture linking .NET applications to core mainframe services.
    Technologies: SOAP, COBOL, JavaScript, VB.NET, Microsoft Visual Studio, ASP.NET, Unit Testing, Banking & Finance, WebSockets, Software Development, Design Patterns, Microservices, C++, .NET, SQL, COM, C#, C#.NET, Architecture, Windows App Development, Windows, ASP.NET MVC, REST APIs

Experience

  • Krew NFT Project
    https://github.com/jrkosinski/krewnime-nft

    Developed and deployed secure and well-tested NFT smart contract and web3 scripts to manage the contract for EVM chains like Ethereum and Polygon in Solidity and for Solana using Metaplex. Listed on Opensea and Magic Eden.

  • Common NFT Contract Design Anti-patterns
    https://medium.com/@john.kosinski/4-common-nft-contract-design-anti-patterns-dd519c02a7af

    Wrote and published an article on the most common design anti-patterns.

    Scanning 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.

  • Ethernaut Solutions
    https://github.com/jrkosinski/Ethernaut

    These are solutions to the well-known Ethernaut problems. Exercises published by OpenZeppelin as teaching tools and to assess one's ability to understand EVM and Solidity security vulnerabilities and how to protect against them. These solutions contain full source code with unit tests and explanations.

  • The Case Against Upgradeability in EVM Smart Contracts
    https://hackernoon.com/the-case-against-upgradeable-smart-contracts

    An article about the benefits and drawbacks of upgradeability in smart contracts in EVM-compatible blockchain environments. The applicability of upgradeable contracts may apply to a narrower set of use cases than is commonly thought.

  • FreshDirect iOS

    An award-winning iOS grocery order/delivery app for the well-known NYC online grocery store, FreshDirect. It was developed with Xamarin iOS.

  • Aquamonix iOS
    https://apps.apple.com/nz/app/aquamonix/id1166491146

    An iOS app that allows customers of Aquamonix to interact remotely with their industrial-sized SCADA irrigation systems. It was developed from scratch using Xamarin iOS.

  • SNY Alexa Skill

    Sports New York (SNY) Alexa Skill retrieves media (audio and video) and plays it via Alexa Echo or Alexa Show (video) regarding the latest news on New York sports teams such as Giants, Jets, Mets, Nets, and the like.

  • Ethereum Oracle Contracts: Can We Trust the Oracle? (Publication)
    The whole point of smart contracts is that they need to be more secure and efficient than traditional contracts. So where do smart contract oracles fit in? In the final installment of our three-part series, Toptal Blockchain Developer John R. Kosinski explains the role of oracles in the evolution of trust.
  • Ethereum Oracle Contracts: Solidity Code Features (Publication)
    Solidity is the programming language of choice for Ethereum and the de facto industry standard for smart contract development. In the second article of our three-part series, Toptal Blockchain Developer John R. Kosinski takes a closer look at Solidity quirks and features, explaining how to make the most of it.
  • Ethereum Oracle Contracts: Setup and Orientation (Publication)
    Oracles are changing the way we view and create smart contracts. How do we implement them in Ethereum, using nothing but Solidity and standard dev tools? In the first article of our three-part series, Toptal Blockchain Developer John R. Kosinski explains how to get started and compile a smart contract with oracles.
  • Get Started With IoT Development: An ESP8266 Arduino Tutorial (Publication)
    In this tutorial, Toptal Freelance Software Engineer John R. Kosinski will demonstrate a simple Amazon Alexa hack using quintessential Arduino skills and basic hardware.

Skills

  • Languages

    C#, JavaScript, C++, C#.NET, Solidity, HTML5, XML, Objective-C, C, Assembly, SQL, TypeScript, C++11, Rust, HTML, VB.NET, Visual Basic, Embedded C++, Go, Python, Java, Perl, PHP, Haskell, GraphQL, Solidity Assembly
  • Frameworks

    .NET, ASP, ASP.NET, .NET Core, ASP.NET MVC, Knockout (Knockout.js), React Native, Unity
  • Libraries/APIs

    Node.js, Amazon API, jQuery, Web3.js, REST APIs, Xamarin.iOS, Mixpanel API, TensorFlow, React, Binance API
  • Tools

    Android Studio, Microsoft Visual Studio, Xcode, Jira, MetaMask, Perforce, NPM, Mongoose, AWS SES, MQTT, SoapUI, Visual Studio
  • Paradigms

    RESTful Development, Agile Software Development, Scrum, REST, Model View Viewmodel (MVVM), Model View Controller (MVC), Design Patterns, Kanban, Unit Testing, Microservices, Windows App Development, Test-driven Development (TDD), Service-oriented Architecture (SOA), Functional Programming, Agile
  • Platforms

    Blockchain, Ethereum, Magento, Linux, Arduino, Amazon Alexa, Android, iOS, Web, Xamarin, Unix, Windows, AWS Lambda, Amazon Web Services (AWS), Blockchain Platforms, AWS IoT, Docker, Visual Studio Code
  • Storage

    JSON, Microsoft SQL Server, MySQL, Amazon DynamoDB, NoSQL, MongoDB
  • Other

    Ethereum Smart Contracts, RESTful APIs, Software Development, Software Architecture, Complex Problem Solving, Full-stack, Crypto, Architecture, Smart Contracts, Xamarin.Forms, SOAP, WebSockets, ESP8266, Internet of Things (IoT), HTTP, eCommerce, Trading, ESP32, Leadership, Technical Leadership, Team Leadership, Lean Project Management, Decentralized Finance (DeFi), APIs, Arbitrage Trading Experience, Blockchain & Cryptocurrency, Cryptocurrency, Algorithms, Rinkeby, AWS EC2, UI, Domain-driven Design (DDD), RESTful Services, Internet Server Application Programming Interface (ISAPI), COM, AWS, Embedded Systems, RTOS, Customized Blockchains, Mailchimp API, Machine Learning, Defect Management, Arbitrage, Futures, Solana, Non-fungible Tokens (NFT), Token Design, Ethers.js, Software, Computer Science, CI/CD Pipelines, Opensea, Bots, DApps, Integration, AWS RDS
  • Industry Expertise

    Banking & Finance

Education

  • PFC USMC in Basic Military Skills
    1996 - 2000
    Parris Island Marine Corps Recruit Depot (MCRD) - Parris Island, SC, USA
  • Bachelor of Science in Computer Science
    1993 - 1998
    University of Delaware - Newark, DE, USA

Certifications

  • Blockchain Platforms
    DECEMBER 2018 - PRESENT
    University at Buffalo & The State University of New York | via Coursera
  • Decentralized Applications (Dapps)
    NOVEMBER 2018 - PRESENT
    University at Buffalo & The State University of New York | via Coursera
  • Smart Contracts
    OCTOBER 2018 - PRESENT
    University at Buffalo & The State University of New York | via Coursera
  • Blockchain Basics
    OCTOBER 2018 - PRESENT
    University at Buffalo & The State University of New York | via Coursera
  • MCT (Microsoft Certified Trainer)
    FEBRUARY 2003 - FEBRUARY 2004
    Microsoft
  • MCSD (Microsoft Certified Solutions Developer)
    MAY 2001 - MAY 2005
    Microsoft

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