Technologies: API Design, Redis, Kue, CouchDB, Express.js, Node.js
- 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.
- Reworked part of the API to serverless (multi-tier AWS Lambda, DynamoDB, RDS).
- Modernized the AWS deployment approach.
Lead Back-end Developer2018 - PRESENTDataMeetPeople
Technologies: WebSockets, Vue.js, MongoDB, PostgreSQL, Aiohttp, Flask, Python
- Migrated an old RoR back end to Flask and MongoDB (via MongoEngine).
- Developed industrial controller data gathering.
- Added UI dashboard using Vue.js and fixed the existing front end.
- Built PostgreSQL DB schema.
- Added data exchange between analytics and real-time data grabbing back ends.
Desktop App Developer2017 - PRESENTAsgard Tutor
Technologies: SQLite, Cairo, GTK+, Boost, C++, Qt
- Designed the API schema.
- Developed the desktop application using Qt 4.
- Added communication to API server.
- Migrated the desktop application to Qt 5.
- Added client-side data storage (initially JSON then migrated to SQLite).
- Supported the app for clients and added new features.
Full-stack Engineer2020 - 2020Ubindi
Technologies: Amazon Web Services (AWS), PostgreSQL, AWS, Elixir, Vue.js
- Added Stripe integration to Vue-based project and appropriate back-end code.
- Added teacher dashboard controls like policy and acceptance workflow and user data update.
- Added dashboard changes promotion to Stripe (when applicable, like currency).
Full-stack engineer2019 - 2020BetterVentures
- Developed the back end for a custom printing application.
- Planned and implemented database models' design. Added a MongoDB schema migrations' infrastructure.
- Added administrative dashboard pages for products, orders, and printers' management.
- Performed code review and refactored legacy or invalid code.
- Added a CircleCI automated test and its integration to the app.
- Added automated code linting and testing before commit.
- Managed a unit testing infrastructure with code refactoring (to make it testable) and mocking (to avoid database or third-party services calls).
- Introduced ElasticSearch integration and reporting.
Front-end Developer2019 - 2020Caplena GmbH
Technologies: APIs, ECharts, Apache, Vuetify.js, Vue.js
- Created a reusable chart component and a custom HTML canvas-based chart.
- Reviewed and refactored Vuex structure to make it clear and avoid "magic strings."
- Added a library of wrappers for Vuetify to match project requirements.
React Native Lead Developer2019 - 2020Medera.ai
Technologies: APIs, Node.js, Redux, React Native
- Designed an API for remote medical diagnosis to be served from AWS Lambda.
- Created and maintained an API by specs using Python/Chalice.
- Built a React Native client for authentication and API calls.
- Migrated a React Native app to Expo and partially re-implemented a messaging system.
- Added OAuth sign in/sign up to a Lambda-based application.
- Deployed the back and front end to an AWS infrastructure (AWS Lambda, DynamoDB, Route53, and more).
Team Leader and Lead Full-stack Developer2019 - 2019Oxstreer
Technologies: Amazon Web Services (AWS), React Redux, React, Docker, ECS, AWS ECR, AWS, Microservices, Node.js
- Reworked a legacy Express.js code for a set of services on the back end.
- Added a new inter-services communication layer with Autodiscovery.
- Rewrote the administrative dashboard from scratch (increasing performance, pagination for large datasets, bug fixing).
- Performed review of React-based shop and prepared list of points to improve.
- Reviewed the UI and added some pixel works for different screen sizes.
- Added the shopping cart module for application using reusable React components.
- Refactored Redux-related modules to remove "magic strings."
- Managed weekly meetings, tracked app development progress.
- Managed the AWS deployment procedure and pipeline automation.
Lead Front-end Developer2019 - 2019San Francisco - Project Evident (via Toptal)
- Supported data extraction and translation from the blogging platform to a custom format.
- Improved the UI/UX of a React-based application.
- Enhanced a Gatsby/Ghost plugin to extract data in an adjusted format.
- Rewrote and optimized GraphQL queries for data fetching.
Lead Full-stack Developer2019 - 2019Pivotal IO
Technologies: Amazon Web Services (AWS), Express.js, MySQL, Bootstrap, Vuetify.js, Vue.js, Node.js
- Designed and structured the overall project management tool.
- Prepared recommendations on tooling and packages.
- Implemented part of the back end.
- Supervised a team of back and front-end developers.
- 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: Blockchain, Amazon Web Services (AWS), React Redux, Docker, Online Payments, AWS, Trading, Cryptocurrency, APIs, React, Express.js, Node.js
- 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: Blockchain, Amazon Web Services (AWS), React Redux, Docker, Online Payments, AWS, Smart Contracts, Solidity, Ethereum, React, Express.js, Node.js
- 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: Blockchain, Distributed Computing, LevelDB, Prototyping, TypeScript, Node.js
- 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: React Redux, APIs, MongoDB, Preact.js
- 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 WebSocket with dynamic node discovering and connection check.
Node.js Back-end Developer2018 - 2018AirBolt (via Toptal)
Technologies: Amazon Web Services (AWS), Hapi.js, Node.js
- Maintained the back end.
- Implemented the database cleanup.
- Reviewed and improved security.
- Reviewed code.
Full-stack Developer2018 - 2018Popchest (via Toptal)
Technologies: Amazon Web Services (AWS), Blockchain, AWS S3, AWS, MongoDB, Express.js, Node.js, Bitcoin
- 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: Amazon Web Services (AWS), React, PDF, PostgreSQL, SQLAlchemy, Alembic, Flask, Python
- 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: Express.js, Node.js, Truffle, Ethereum
- 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: React, Express.js, Node.js, Truffle, Ethereum
- Gathered requirements for smart-contract and back-end code.
- Developed a smart contract to collect ether and store jackpot players.
- Built the back end for the site.
- Created a front-end prototype that worked with both the back end and contract events using React.
- Prepared deployment documentation for the site (deployed on Heroku) and Ethereum standalone mode.
- Generated a contract management dashboard.
- Conceived minor specific UI controls for the front end using React, like lottery wheel, carousel, among other playing features.
Software Developer2017 - 2017AirBolt, Pty., Ltd. (via Toptal)
Technologies: Amazon Web Services (AWS), AWS EC2, AWS S3, Hapi.js, Node.js, MongoDB
- 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: AWS S3, Heroku, CSS3, Bootstrap, HTML5, Web Audio API, Django, Python 3
- Created an audio guide plugin for forms.
Node.js Developer2017 - 2017Algolibs
Technologies: MongoDB, jQuery, Express.js, Node.js
- Developed 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: REST APIs, Amazon MWS, Flask, Python
- 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: PostgreSQL, Caching, Redis, Webpack, Bootstrap, Knockout.js, Express.js, Node.js
- Created an API with OAuth for the existing site to provide desired data externally.
- Secured the API with request rate and IP per minute.
- Developed key infrastructure and UI dashboard to help users maintain access keys and secrets.
- Added automated deployment scripts.
- Maintained existing back-end code and database (PostgreSQL).
- Embedded API intermediate results caching using Redis.
Freelance Lead Python Developer2016 - 2016Pickett (via Toptal)
Technologies: Amazon Web Services (AWS), AWS S3, AWS EC2, AWS, MySQL, Bootstrap, jQuery, Flask, Python
- 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.
- Appended 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: PyMongo, MongoEngine, MongoDB, Flask, Python, Push Notifications
- Created a UI for user management.
- Developed an engine for static content handling.
- Maintained a back-end application.
- 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: SQLAlchemy, Flask, Python
- Assembled API specifications and protocols.
- Set up the environment and automatic deployment script.
- Prepared tests for future API endpoints and methods (integration and unit tests).
- Created 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: Oracle, Microsoft SQL Server, Durandal, ASP.NET, C#
- 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: Microsoft Enterprise Library, C#, .NET
- Implemented a thick client.
- Provided coverage for unit tests.
- Reviewed code.
- Developed Asterisk modules.
- Introduced logging via a logging application block.