Technologies: Node.js, Express.js, CouchDB, Kue, Redis, API Design
- Maintained the Node.js back end.
- Planned a new API structure.
- Migrated old code to a modern runtime.
- Made deployments to an AWS stack.
- Prepared test infrastructure (deployment, automated testing suite, test structure).
- Integrated with third-party services and analytics.
React Native Lead Developer2019 - 2019Telemedy
Technologies: React Native, Redux, Node.js, API
- Designed an API for remote medical diagnosis.
- Created and maintained an API by specs.
- Created a React Native client for API.
- Migrated a React Native app to Expo.
Lead Front-end Developer2019 - 2019San Francisco - Project Evident (via Toptal)
- Supported data extraction and translation from blogging platform to custom format.
- Improved the UI/UX of a React-based application.
- Enhanced a Gatsby/Ghost plugin to extract data in adjusted format.
- Rewritten and optimized GraphQL queries for data fetching.
Lead Full-stack Developer2019 - 2019Pivotal IO
Technologies: Node.js, Vue, Vuetify, Vue-Bootstrap, MySQL, Express.js
- Created the overall project management tool design and structure.
- Prepared recommendations on tooling and packages.
- Implemented part of the back end.
- Supervised a team of back- and front-end devs.
- Migrated the application UI from Vue-Bootstrap to Vuetify.
- Maintained the application after going to alpha version.
- Created a React Native client for an existing API.
Full-stack and Blockchain Developer2018 - 2019Pukkamex, LLC
Technologies: Node.js, Express.js, React, API, Cryptocurrency, Trading, AWS, Payments, Docker
- Prepared architecture and design for a cryptocurrency copy-trading portal.
- Designed an API for a copy trading portal.
- Implemented an API according to specs and hardened it against potential security issues.
- Created a responsive React front end.
- Added real-time dataflow via websockets.
Lead Developer2018 - 2019Primebet (Fractional Media)
Technologies: Node.js, Express.js, React, Ethereum, Solidity, Smartcontracts, AWS, Payments, Docker
- Implemented smart contracts from scratch to provide a sports betting feature.
- Optimized Ethereum smart contracts to minimize consumed gas.
- Developed communication between the Ethereum network and the Node.js back end.
- Developed a multi-tier back end to maintain sport games, scores, bidders, and outcome calculation.
- Created a React front end for a sports site.
- Implemented integration with third-party APIs (SportRadar, FantasyData).
- Created background workers to keep data up to date.
- Created deployment procedures and scripts to promote the app to Amazon infrastructure.
Node.js Developer2018 - 2019MyFocus, LLC (via Toptal)
Technologies: Node.js, TypeScript, Prototyping, LevelDB, Blockchain, Distributed Communications, Torrent
- Created a distributed file sharing system based on modified BitTorrent/Kademlia protocol.
- Added different network transport layers like UDP4, UDP6, and Bluetooth.
- Redesigned and created file splitting and hashing to promote to network.
- Added file discovery methods and multi-regional support for faster content retrieval.
Senior React/Preact Engineer2018 - 2019404publishing (via Toptal)
Technologies: Prect, Preact SSR, MongoDB, API
- Optimized Preact SSR rendering time.
- Implemented an API to access dynamically changed data.
- Created and maintained the websocket communication layer with reconnections, heartbeat, and data consistency check.
- Created and maintained a mesh network based on websockets with dynamic node discovering and connection check.
Node.js Back-end Developer2018 - 2018AirBolt (via Toptal)
Technologies: Node.js, HAPI
- Maintained the back end.
- Implemented the database cleanup.
- Reviewed and improved security.
- Reviewed code.
Full-stack Developer2018 - 2018Popchest (via Toptal)
Technologies: Bitcoin, Bcoin, Node.js, Express.js, MongoDB, AWS, S3
- Provided full-node support and multi-tier deployment support for Bitcoin.
- Fixed Bitcoin-related issues.
- Implemented a new payment feature.
- Implemented tests for Bitcoin and wallets.
Back-end Python Engineer2017 - 2018Successkit.io (via Toptal)
Technologies: Python, Flask, Alembic, SQLAlchemy, PostgreSQL, PDF, React
- Supported the Python back end.
- Improved database migration scripts via Alembic.
- Fixed PostgreSQL-specific issues in the database layer.
- Improved and extended existing functionality.
- Added PDF export of reports.
- Extended existing React controls to reflect back-end changes.
Ethereum Developer2017 - 2018SilverToken (via Toptal)
Technologies: Ethereum, Truffle, Web3, Node.js, Express.js
- Implemented smart contracts and tokens.
- Implemented back-end features using Express.js with JWT authentication.
- Tested pre-ICO technology.
- Launched and maintained the ICO.
- Migrated and optimized contracts.
Ethereum and Back-end Developer2017 - 2018OG Mobi (via Toptal)
Technologies: Etherem, Truffle, Web3, Node.js, Express.js, React
- Gathered requirements for smart-contract and back-end code.
- Created a smart contract to collect ether and store jackpot players.
- Created the back end for the site.
- Create a front-end draft that worked with the back end and contract events using React.
- Prepared deployment documentation for the site (deployed on Heroku) and Ethereum standalone mode.
- Created a contract management dashboard.
- Created minor specific UI controls like lottery wheel, carousel, and so on for the front end using React.
Software Developer2017 - 2017AirBolt, Pty., Ltd. (via Toptal)
Technologies: MongoDB, Node.js, Hapi.js AWS, S3, EC2
- Enhanced an authentication service in a Node.js application empowered with Hapi.
- Maintained a MongoDB database, fixed consistency, and added constraints.
- Added the administrative part using React for the front end over the existing API.
- Extended the API for the administrative part.
- Prepared deployment and maintenance documentation.
- Refactored and cleaned up the code.
Freelance Full-stack Developer2017 - 2017The Vaan Group (via Toptal)
Technologies: Python 3, Django, AudioAPI, HTML5, Bootstrap, CSS3, Heroku, Amazon S3
- Created an audio guide plugin for forms.
Node.js Developer2017 - 2017Algolibs
Technologies: Node.js, Express.js, jQuery, MongoDB
- Created a color search engine that allows users to get images relevant to one or more colors.
- Created image collectors to gather sample data (at least a million images' worth of data) stored in MongoDB from existing images.
- Extended color search engine to allow search by hue value (median).
- Prepared deployment documentation.
Freelance Python Developer2016 - 2017Forecastly (via Toptal)
Technologies: Python, Flask, Amazon MWS, REST API
- Added an Amazon Inbound Shipment fulfillment interface to www.github.com/czpython/python-amazon-mws.
- Supported the site using Flask, Bootstrap, and Flask-Bootstrap packages.
- Refactored and cleaned up code.
- Provided a suggestion for migration from Pony ORM to SQLAlchemy, pointing to potential caveats and bonuses according to the customer's requirements.
Back-end API Developer2016 - 2016NDA
Technologies: Node.js, Express.js, Knockout.js, Bootstrap, Webpack, Redis, Caching, Postgres
- Created an API with OAuth for the existing site to provide desired data externally.
- Secured the API with request rate and IP per minute.
- Created key infrastructure and UI dashboard to help users maintain access keys and secrets.
- Added automated deployment scripts.
- Maintained existing back-end code and database (Postgres).
- Added API intermediate results caching using Redis.
Freelance Lead Python Developer2016 - 2016Pickett (via Toptal)
Technologies: Python, Flask, jQuery, Bootstrap, MySQL, AWS, Amazon EC2, Amazon S3
- Prepared technology stack suggestions. Developed site and database architecture documents.
- Created the site using Python/Flask and MySQL.
- Supported UI according to design guidelines.
- Added a database migration engine and supported multiple database branch migration processes.
- Introduced tests (WebDriver and PyUnitTest) and covered the entire application.
- Added a data scraper from different sources (HTML pages and APIs).
- Prepared multi-tier deployment documentation and supported automatic deployment to Amazon EC2 instances.
- Optimized Amazon instance performance and cost.
Freelance Programmer2015 - 2016Medify, Ltd. (via Toptal)
- Modified the Anki flashcard app to help users concentrate on their weakest topics.
Senior Python Developer2014 - 2016Steppechange
Technologies: Push Notifications, Python, Flask, MongoDB, MongoEngine, PyMongo, Flask Extensions
- Created a UI for user management.
- Created an engine for static content handling.
- Maintained an application back end.
- Introduced asset bundling and versioning.
- Implemented a preview of Windows 8 tiles for different modes (cycle, slide, flip, etc.) via jQuery and jQueryUI.
Back-end API Developer2015 - 2015Perigee
Technologies: Python, Flask, SQLAlchemy
- Prepared API specifications and protocols.
- Prepared the environment and automatic deployment script.
- Prepared tests for future API endpoints and methods (integration and unit tests).
- Create an API server according to specs and tests.
- Adjusted the API to meet iOS app requirements.
- Made some change requests to improve application functionality.
- Worked closely with the front-end team to fix issues.
Technical Leader2010 - 2014Exigen Services/Return on Intelligence
Technologies: C#, ASP.NET, Durandal, MS SQL, Oracle
- Created and maintained the UI for management of client bonus and benefit groups.
- Refactored database structure. Introduced Entity Framework to the application. Fixed bottlenecks in requests.
- Added client-side validation via jQuery validation.
- Maintained unit tests.
- Optimized SQL scripts.
C# Developer2007 - 2008Astra Software
Technologies: .NET, C#, AsteristPBX, Enterprise Library
- Implemented a thick client.
- Provided coverage for unit tests.
- Reviewed code.
- Developed Asterisk modules.
- Introduced logging via a logging application block.