Senior Ruby on Rails and Node.js Developer2020 - 2022Freelance
Technologies: Ruby on Rails (RoR), JRuby, Java, Python, PostgreSQL, Citus, Sidekiq, Redis, Stimulus, Haml, HTML, SCSS, CSS, Highcharts Stock, Highcharts, Docker, Amazon ECS (Amazon Elastic Container Service), AWS CloudFormation, CircleCI, Node.js, TypeScript, React, TradingView, MongoDB, Amazon EC2 (Amazon Elastic Compute Cloud), Jest, DevOps
- Implemented high-performance bots for arbitrage and market-making on centralized and decentralized cryptocurrency exchanges.
- Developed a dynamic distributed algorithm for efficient backtesting of automated Forex trading strategies over a large volume of historical data.
- Designed distributed sharded database for efficient querying and storage of billions of records. Implemented import of tick, bar, and indicator data from third-party Forex feeds.
- Built reporting dashboards and charts with React and TradingView.
Senior Ruby on Rails Developer2018 - 2019Jungle Scout
- Launched a marketplace platform based on open-source Sharetribe for Amazon Freelancers offering services to Amazon Sellers.
- Implemented complex Stripe integration for a marketplace charging service and processing fees using managed and custom Stripe accounts, on-behalf charges, transfers, payouts, and partial and full refunds.
- Developed multi-step checkout and abandoned cart notifications, which led to improved sales.
- Built a highly demanded attachments feature for freelancer-client chat, which quickly grew to hundreds of thousands of files stored in and served from AWS S3.
- Integrated Google Tag Manager and Google Analytics with custom dimensions, metrics, and events to measure the impact of rolled-out features.
- Built a listing WYSIWIG editor based on Basecamp's open-source Trix to improve the quality of listings.
- Redesigned the front-end according to brand guidelines. Used Litmus to improve HTML email templates to be responsive and support a wide range of email clients, including Outlook.
- Introduced Cypress end-to-end acceptance tests and improved unit test coverage.
- Implemented Stripe charge metadata for accounting and financial reports in Stripe Sigma.
- Contributed to the upstream open-source Sharetribe project with bug fixes.
Senior Ruby on Rails Developer2015 - 2017Diagnotes, Inc. (via Toptal)
- Developed a HIPAA-compliant healthcare text, audio, and video communication platform for medical providers and patients.
- Built web video chat and encrypted video archiving.
- Created and integrated an ActiveRecord library for efficient and seamless data encryption and decryption using Pgcrypto and AWS KMS.
- Built LDAP authentication and synchronization of ActiveDirectory users, and also SAML SSO with ADFS.
- Implemented tree-based user group hierarchy with inherited permissions and efficient ways of querying them utilizing the materialized path pattern.
- Introduced browser-driven end-to-end acceptance tests and contributed to overall test coverage boost up to 94%.
- Worked on a RESTful JSON API consumed by iOS and Android client applications.
- Migrated the application from Rails 4 to Rails 5.
Senior Ruby on Rails Developer2014 - 2015Unityaid Pty, Ltd.
Technologies: Ruby on Rails (RoR), CoffeeScript, jQuery, Haml, HTML5, Sass, CSS3, Bootstrap, Sidekiq, PostgreSQL, RSpec, Capybara, Selenium WebDriver, Backbone.js, Amazon S3 (AWS S3), Amazon CloudFront CDN, Redis, Heroku, Facebook API, Twitter API, New Relic
- Led the development of a crowdfunding web application to successful launch in five months.
- Integrated Stripe Connect and credit card processing on behalf of merchant accounts which also involved support for multiple countries and currencies and refund processing using Stripe webhooks.
- Created a dashboard to monitor campaign progress and manage contributions.
- Developed and maintained an extensive integration and browser test suite covering major application features and workflows.
- Implemented a responsive UI, which proved to be a breaking point for the application as 66% of visitors are smartphone and tablet users.
Lead Ruby on Rails Developer2011 - 2013OK Venue, LLC
Technologies: Ruby on Rails (RoR), CoffeeScript, jQuery, Haml, HTML5, Sass, CSS3, Bootstrap, Delayed Job, PostgreSQL, MySQL, RSpec, Capybara, Selenium WebDriver, Twilio API, Facebook API, Twitter API, Linode, Cloudflare, New Relic, Airbrake, QR Codes
- Created a web application to create and manage events and sell tickets. Managed a successful product launch: hosting of New York SOHO International Film Festival screenings in 2013.
- Implemented a QR code ticket generation mechanism and ticket delivery via email (Postmark API), text message (Twilio API), and picture message (Mogreet API). Created and open-sourced a Ruby Gem for sending picture messages (MMS) with Mogreet.
- Integrated secure credit card processing with Braintree API using client-side encryption. Integrated ACH payments with Transmodus API, allowing event owners to withdraw ticket sales income.
- Architected and implemented REST microservices and embeddable Rails::Engine modules allowing for white labeling of the product.
- Implemented short URL tracking and analytics allowing event curators to identify the most efficient marketing campaigns, channels, and tastemakers.
- Led the development of a web application for activating and managing decoupled debit cards.
Senior Ruby on Rails Developer2008 - 2012MD Consulting
Technologies: Ruby on Rails (RoR), JRuby, Ruby, CoffeeScript, jQuery, Backbone.js, Raphaël, HTML5, Haml, CSS3, Sass, Bootstrap, OLAP, Pentaho Mondrian OLAP Engine
- Created a web application for analyzing arbitrary multi-dimensional data using OLAP cubes.
- Developed a customizable dashboard for visualizing and analyzing complex financial data.
- Created custom UI web components using a Raphael JS library.
- Advised on the design and implementation of TextMagic API and Ruby wrapper library for sending text messages.
- Implemented a web scraper for importing and synchronizing job listings from http://nav.no into a Scandinavian job search index.
- Created a Facebook quiz application for Richmond University to help future students select their major subject based on quiz answers.
Ruby on Rails Developer2009 - 2011SmartSites, LLC
- Created a web application for grading and improving resumes.
- Implemented a scoring and profiling algorithm based on uploaded resume documents.
- Created a Ruby gem and web service hosted on Windows Server for analyzing MS Word documents using Win32 OLE interface.
- Developed a web application for creating online resumes.
Ruby on Rails Developer2010 - 2010Netronix, Inc.
- Developed a web application for remote monitoring of environmental data (including weather, wind, water quality, temperature, flow, and depth).
- Led the transition of a beta product to production state with its first paying customers.
- Created a multi-threaded Ruby server listening for measurement data sent by remote sensors over Iridium satellite. The costly satellite bandwidth required the development of a custom low-footprint communication protocol over TCP/IP.
- Implemented a customizable dashboard with real-time charts displaying incoming telemetry data.
- Provided a module allowing the user to remotely configure sensors via the web interface.
- Implemented alert rules and notification via SMS and/or email (like water depth at node y > x).
Senior Ruby on Rails Developer2009 - 2010Umongous, Inc.
- Developed the back end of a web application for online surveys.
- Implemented an anti-bot mechanism preventing bots from taking surveys.
- Created a logic and administration interface for demographic surveys.
- Redesigned key database schema entities and ActiveRecord objects for better maintainability.
- Optimized MySQL queries for high-traffic requirements using MySQL slow logs.
J2EE Designer and Developer2007 - 2008Infovide-Matrix
Technologies: Java, Jakarta EE, IBM WebSphere, Eclipse RCP, Eclipse Modeling Framework (EMF), XML Schema, CORBA
- Developed a functional tester in Eclipse RCP for a telecommunication company.
- Implemented a Corba-to-XML and XML-to-Corba object mapper based on XML Schema and IDL files.
- Wrote a mechanism for rendering message input forms in Eclipse RCP based on XML Schema.
- Designed and implemented a web application supporting recruitment workflow (WebSphere Business Modeler, WebSphere Integration Developer, WebSphere Process Server).
Java Developer in Pricing and Workflow2006 - 2007J.P. Morgan Chase
Technologies: Java, Jakarta EE, Eclipse RCP, JUnit, Spring, BEA AquaLogic Service Bus, XML
- Developed a complex Eclipse RCP option pricer application in the equity exotics and hybrids department.
- Conducted workflow modeling and implementation in BEA AquaLogic BPM.
- Designed and implemented a client-server application for publishing financial instruments.
- Integrated the client application with an external workflow server.
- Worked in Agile methodology involving daily scrums.
J2EE and PL/SQL Developer2004 - 2006Syndatis
- Designed and developed business process management (BPM) web applications that implement contract and expense workflows for pharmaceutical companies.
- Designed and implemented a module for the reconciliation of employee American Express credit cards.
- Analyzed business workflows and prepared functional and technical specifications in Waterfall methodology.