Senior Node.js Developer2017 - PRESENTVinus
- Developed an automated cash-and-carry arbitrage trading system for cryptocurrency exchanges. Supports Bitmex and Bitfinex, several types of trading (mainly cash-carry arbitrage) supported.
- Built a system of three Node.js applications on Heroku and several AWS lambdas over the course of a few months to implement a unique marketing "sell-it-before-implementing-it" system.
- Created an on-the-fly image generator using Node.js with Gifsicle and WebShot to generate customized promotional "coins" for use on the site.
Mobile Developer (Remote)2014 - PRESENTDoor3/FreshDirect
Technologies: Xamarin iOS, Objective-C iOS, Java Android, Xamarin Android, .NET, Selendroid, Jira, Scrum
- 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.
IoT Engineer2018 - 2019Jaber Medical
Technologies: IoT, C++, Arduino, Node.js, AWS, DynamoDB, Embedded, ESP8266, ESP32
- Contributed to networked embedded development on IoT devices that were connected to a central server; not at liberty to discuss details at the moment.
Alexa Developer2018 - 2018Anguleris Technologies
Technologies: Alexa, AWS, Node.js
- Developed a rich Alexa app that will allow customers to run spoken English queries against a complex product database.
Alexa Developer2017 - 2018Sterling VC
Technologies: Alexa, Node.js, AWS
- Developed and brought to market an Alexa skill for retrieving New York sporting news updates.
R&D Manager2017 - 2018Futronix
Technologies: IoT, Alexa, AWS, ESP8266, Embedded C++, Arduino
- 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.
Freelance Senior Xamarin Developer2015 - 2017Under NDA (via Toptal)
Technologies: Xamarin iOS, WebSockets
- 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.
Senior Developer | Team Leader2012 - 2014Manao Software
Technologies: .NET, REST Services, JSON, MVVM, Knockout.js, jQuery, Soap UI, TDD, Scrum, JIRA, Perforce, DDD
- Managed a team of developers to produce a REST/JSON front-end to a unique SAP-querying interface.
- 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.
Software Development Manager2009 - 2012HotelTravel.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.
Senior Developer2007 - 2009Morgan Stanley (NYC)
- Performed the application and web service programming in C# and VB.NET.
- Interfaced .NET software with legacy COBOL programs.
- Developed software to manage fixed income securities based on currency exchange models.
- Designed service-based architecture linking .NET applications to core mainframe services.
Senior Software Architect2003 - 2007Braveline Technology (NYC)
Technologies: C#, VB.NET, C++, VB6, SOA
- Developed an internal image server that's still in use and well-regarded.
- Wrote an eCommerce object-oriented redesign.
- Developed an internal component library (parts of which are still in use).
- Serviced clients in various industries including private equity, financial services, entertainment, and accounting.
Junior Instructor2001 - 2003SetFocus LLC (NYC)
Technologies: .NET, SQL Server, COM
- Researched topics to present to students.
- Assisted the senior instructor in preparing course material.
- Delivered and and helped to deliver course material to students.
- Assessed and graded students' work.
- Became MCT certified.
- Bitcoin Payments (Development)https://github.com/jrkosinski/bitcoin-payments
A simple Bitcoin payment acceptance module in Node.js for self-educational and demonstration purposes. It creates a wallet address, monitors the Bitcoin network for payment and confirmation, and broadcasts events for progress notifications.
- Crypto Champ (Development)https://github.com/jrkosinski/crypto-champ
An implementation of an Ethereum smart contract and associated Oracle for self-educational and demonstration purposes. It accepts bets for fictitious boxing matches then calculates and distributes winnings. It also includes a web3.js front-end (which is still in development as of this writing).
- Minacoin (Development)https://github.com/jrkosinski/minacoin
This is a broad-strokes example—for educational purposes only—of the very basic essential workings of a cryptocurrency, coded in Node.js. It includes a Blockchain functionality, a P2P distribution, and a test client; based on the Bitcoin model.
- Happy-try-catch (Development)https://github.com/jrkosinski/happy-try-catch
A generic try/catch/finally library utility module for Node.js. It is also available on npm: Npmjs.com/package/happy-try-catch.
- Node.js: Async-interval-time (Development)https://github.com/jrkosinski/async-interval-timer
A generic library utility module for the timing of synchronous or asynchronous tasks. It is also available on npm: Npmjs.com/package/async-interval-timer.
- Esp8266-discovery (Development)https://github.com/jrkosinski/esp8266-discovery
A generic example for the discovery of an esp8266 on the WiFi network; includes an Android client and esp8266 (Arduino) code.
- IoT/Alexa Demo (Development)https://github.com/jrkosinski/AlexaTvRemote
This is an IoT demo. This is code to control your Samsung TV remote to turn your TV off and on, using an Echo device and code embedded on an ESP8266 chip.
Associated with Toptal blog article: Toptal.com/arduino/esp8266-arduino-tutorial-alexa-hack.
- 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.
Frameworks.NET, ASP, ASP.NET, Machine Learning, Knockout.js, Sencha Touch
Libraries/APIsNode.js, Amazon API, jQuery, MailChimp API, Mixpanel API, TensorFlow, Keras
ToolsAndroid Studio, Microsoft Visual Studio, Mongoose, Xcode, Jira, Arduino IDE, NPM, AWS SES, MQTT, SoapUI
ParadigmsAgile Software Development, Scrum, REST, Model View Viewmodel (MVVM), Model View Controller (MVC), Design Patterns, Kanban
StorageJSON, Microsoft SQL Server, MySQL, NoSQL, MongoDB
OtherRESTful APIs, Smart Contracts, Ethereum Smart Contracts, Blockchain Technology, Xamarin Forms, SOAP, WebSockets, ESP8266, Internet of Things (IoT), HTTP, eCommerce, Trading, Banking & Finance, ESP32, RTOS, Customized Blockchains, Unix Shell Scripting, IoT Protocols
PlatformsAWS IoT Core, Linux, Arduino, Amazon Alexa, Android, iOS, Blockchain, Web, Xamarin, Blockchain Platforms, AWS IoT
- Bachelor of Science degree in Computer Science1993 - 1998University of Delaware - Newark, DE, USA
- PFC USMC in Basic Military Skills1996 - 1996Parris Island Marine Corps Recruit Depot (MCRD) - Parris Island, SC, USA
- MCT (Microsoft Certified Trainer)FEBRUARY 2003 - FEBRUARY 2004Microsoft
- MCSD (Microsoft Certified Solutions Developer)MAY 2001 - MAY 2005Microsoft