toptal.com
Contact us: +1.888.604.3188
Mateusz Dominiak, Ruby on Rails Developer in Warsaw, Poland
Mateusz Dominiak

Ruby on Rails Developer in Warsaw, Poland

Member since November 18, 2014
Matt is a senior web developer and architect with sixteen years of experience. His core competency lies in end-to-end architecting and development of web applications through all phases from the ground up. He has a proven track record of successful product launches working remotely for technology startups for the past eleven years.
Mateusz is now available for hire
Hire Mateusz

Portfolio

  • Freelance
    Ruby on Rails (RoR), JRuby, Java, Python, PostgreSQL, Citus, Sidekiq, Redis...
  • Jungle Scout
    Ruby on Rails (RoR), Ruby on Rails 5, Stripe API, Stripe Connect API...
  • Diagnotes, Inc. (via Toptal)
    Ruby on Rails (RoR), Ruby, Resque, PostgreSQL, RSpec, Pgcrypto, Capybara...

Experience

Location

Warsaw, Poland

Availability

Part-time

Preferred Environment

Amazon Web Services (AWS), Sublime Text 3, Visual Studio Code, Docker, AWS, Git, MacOS, DataGrip, CircleCI, Pivotal Tracker, Slack

The most amazing...

...thing I've built is a multi-threaded server collecting telemetry measurements from remotely deployed sensors with a low-footprint custom communication protocol.

Employment

  • Senior Ruby on Rails Developer

    2020 - 2020
    Freelance
    • 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 with Highcharts and Highcharts Stock.
    Technologies: Ruby on Rails (RoR), JRuby, Java, Python, PostgreSQL, Citus, Sidekiq, Redis, Stimulus, Haml, HTML, SCSS, CSS, Highcharts Stock, Highcharts, Docker, AWS ECS, AWS CloudFormation, CircleCI

  • Senior Ruby on Rails Developer

    2018 - 2019
    Jungle 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/custom Stripe accounts, on-behalf charges, transfers, payouts, and partial and full refunds.
    • Developed a 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.
    Technologies: Ruby on Rails (RoR), Ruby on Rails 5, Stripe API, Stripe Connect API, Stripe Webhooks, Stripe Sigma, Stripe Radar, Sphinx Search Engine, Memcached, Pundit, OmniAuth, Facebook Login, Google Login, Google Places API, Google Analytics API, ActiveCampaign, Devise, Delayed_job, iDevAffiliate API, AWS S3, AWS SES, Amazon Aurora, MySQL, Amazon CloudFront CDN, Heroku, RSpec, Cypress.io, Sentry, JavaScript, React, Node.js, SCSS, Haml, Bootstrap, Chrome Extensions, CircleCI

  • Senior Ruby on Rails Developer

    2015 - 2017
    Diagnotes, Inc. (via Toptal)
    • Developed a HIPAA-compliant healthcare text/audio/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/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/Android client applications.
    • Migrated the application from Rails 4 to Rails 5.
    Technologies: Ruby on Rails (RoR), Ruby, Resque, PostgreSQL, RSpec, Pgcrypto, Capybara, AWS S3, AWS Key Management Service (KMS), AWS Push Notification Service (AWS SNS), AWS SES, Elasticsearch, Amazon CloudFront CDN, Redis, OpenTok, Pusher, Flowplayer, SemaphoreCI, New Relic, JavaScript, React, jQuery, Haml, Sass, CSS3, Bootstrap 4, Bootstrap 3

  • Senior Ruby on Rails Developer

    2014 - 2015
    Unityaid Pty, Ltd.
    • Led 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/currencies and refund processing using Stripe web hooks.
    • Created a dashboard to monitor campaign progress and manage contributions.
    • Developed and maintained an extensive integration/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/tablet users.
    Technologies: Ruby on Rails (RoR), CoffeeScript, jQuery, Haml, HTML5, Sass, CSS3, Bootstrap, Sidekiq, PostgreSQL, RSpec, Capybara, Selenium WebDriver, Backbone.js, AWS S3, Amazon CloudFront CDN, Redis, Heroku, Facebook API, Twitter API, New Relic

  • Lead Ruby on Rails Developer

    2011 - 2013
    OK Venue, LLC
    • Created a web application to create/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.
    Technologies: Cloudflare, 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, New Relic, Airbrake

  • Senior Ruby on Rails Developer

    2008 - 2012
    MD Consulting
    • 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.
    Technologies: Ruby on Rails (RoR), JRuby, Ruby, CoffeeScript, jQuery, Backbone.js, Raphaël, HTML5, Haml, CSS3, Sass, Bootstrap, OLAP, Pentaho Mondrian OLAP Engine

  • Ruby on Rails Developer

    2009 - 2011
    SmartSites, 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.
    Technologies: Ruby on Rails (RoR), JavaScript, HTML, CSS, Delayed_job, CanCan, Haml, Liquid, Airbrake, Capistrano, Shoulda, Factory Girl, Paperclip, Nokogiri

  • Ruby on Rails Developer

    2010 - 2010
    Netronix, 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 web interface.
    • Implemented alert rules and notification via SMS and/or email (like water depth at node y > x).
    Technologies: Ruby on Rails (RoR), Ruby, HTML, Sass, CSS, JavaScript, Highcharts, Prototype Framework, Airbrake, Capistrano, Twilio API

  • Senior Ruby on Rails Developer

    2009 - 2010
    Umongous, 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.
    Technologies: Ruby on Rails (RoR), JavaScript, jQuery, MySQL, HTML, CSS

  • J2EE Designer and Developer

    2007 - 2008
    Infovide-Matrix
    • 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).
    Technologies: Java, Core Java (J2EE), IBM WebSphere, Eclipse RCP, Eclipse Modelling Framework (EMF), XML Schema, CORBA

  • Java Developer in Pricing and Workflow

    2006 - 2007
    J.P. Morgan Chase
    • 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.
    Technologies: Java, Core Java (J2EE), Eclipse RCP, JUnit, Spring, BEA AquaLogic Service Bus, XML

  • J2EE, PL/SQL Developer

    2004 - 2006
    Syndatis
    • Designed and developed BPM web applications that implement contract/expense workflows for pharmaceutical companies.
    • Designed and implemented a module for reconciliation of employee American Express credit cards.
    • Created a relational database.
    • Analyzed business workflows and prepared functional and technical specifications in waterfall methodology.
    • Organized training for new users.
    Technologies: JavaScript, CSS, HTML, Apache Velocity, Torque, Core Java (J2EE), Microsoft SQL Server, Oracle RDBMS, PL/SQL

Experience

  • Jungle Scout Market (Development)
    https://market.junglecout.com

    Jungle Scout Market is a marketplace platform based on open-source Sharetribe for Amazon Freelancers offering services to Amazon Sellers. I was a full-stack Ruby on Rails developer responsible for successfully launching the project, continuously implementing, deploying, and monitoring new features, working closely with the product manager, CTO, and customer support.

  • Diagnotes (Development)
    https://www.diagnotes.com

    A web application for secure healthcare communication.

  • OK Venue (Development)
    https://okvenue.com

    A web application for creating events and selling tickets.

  • InstantCashSweepstakes (Development)
    http://instantcashsweepstakes.com/

    A web application for online surveys coupled with online market research web application http://aytm.com.

  • Environet (Development)
    https://ienvironet.com/

    A web application for remote monitoring in the environment sector.

  • Utilizing Agent Teams in Grid Resource Brokering | Academic Publication (Other amazing things)
    http://www.ibspan.waw.pl/~paprzyck/mp/cvr/research/agent_papers/MAGS_2007.pdf

    M. Dominiak, M. Ganzha, M. Gawinecki, W. Kuranowski, M. Paprzycki, S. Margenov, I. Lirkov, Utilizing Agent Teams in Grid Resource Brokering, International International Transactions on Systems Science and Applications, Vol. 3, No. 4, 2008, 296-306.

  • Selecting Grid-agent-team to Execute User-job — Initial Solution | Academic Publication (Other amazing things)
    http://www.ibspan.waw.pl/~paprzyck/mp/cvr/research/agent_papers/ARES_2007.pdf

    M. Dominiak, M. Ganzha, M. Paprzycki, Selecting grid-agent-team to execute user-job — initial solution, Proceedings of the Conference on Complex, Intelligent and Software Intensive Systems, IEEE CS Press, Los Alamitos, CA, 2007, 249-256.

  • Efficient Matchmaking in an Agent-based Grid Resource Brokering System | Academic Publication (Other amazing things)
    http://www.ibspan.waw.pl/~paprzyck/mp/cvr/research/agent_papers/wisla_06.pdf

    M. Dominiak, W. Kuranowski, M. Gawinecki, M. Ganzha, M. Paprzycki, Efficient Matchmaking in an Agent-based Grid Resource Brokering System, Proceedings of the International Multiconference on Computer Science and Information Technology, PTI Press, 2006, 327-335.

  • Utilizing Agent Teams in Grid Resource Management ... | Academic Publication (Other amazing things)
    http://www.ibspan.waw.pl/~paprzyck/mp/cvr/research/agent_papers/JVA_06.pdf

    M. Dominiak, W. Kuranowski, M. Gawinecki, M. Ganzha, M. Paprzycki, Utilizing agent teams in grid resource management — preliminary considerations, Proceedings of the IEEE J. V. Atanasoff Conference, IEEE CS Press, Los Alamitos, CA, 2006, 46-51.

Skills

  • Languages

    Ruby, HTML, SQL, HTML5, Sass, CoffeeScript, CSS3, Haml, CSS, JavaScript, SAML, Java, JRuby, Core Java (J2EE), XML, SCSS, UML, C, C++, Assembler, Lisp, Haskell, SAS, Python, TypeScript 2, TypeScript, ECMAScript (ES6)

  • Frameworks

    Ruby on Rails 5, Ruby on Rails 4, Ruby on Rails (RoR), Capybara, Bootstrap, Swagger, OAuth 2, minitest, Prototype Framework, Factory Girl, Apache Velocity, JUnit, Spring, Eclipse Modelling Framework (EMF), Cypress.io, Bootstrap 2, Bootstrap 3, Bootstrap 4, Ruby on Rails 3, Stimulus, AngularJS, Angular

  • Libraries/APIs

    Ruby ERB, Pusher, API Development, Resque, Ruby on Rails API, Nokogiri, CarrierWave, Devise, Highcharts, jQuery, Sidekiq, Stripe, WebRTC, PubNub, React, Twilio API, Braintree API, Selenium WebDriver, OmniAuth, Backbone.js, Raphaël, Liquid, Stripe API, Stripe Connect API, Pundit, Facebook Login, Google Places API, Google Analytics API, Node.js, Moment.js, D3.js, Google Maps, Paperclip, Facebook API, Mandrill API, Mongoid, Twitter API, PayPal API

  • Tools

    Git Flow, SemaphoreCI, GitHub, RSpec, Nginx, AWS SDK, Rubocop, AWS Push Notification Service (AWS SNS), AWS SES, Capistrano, Git, Citus, Amazon CloudFront CDN, Airbrake, Torque, Eclipse RCP, Sublime Text 3, ITerm, Sentry, CircleCI, AWS Key Management Service (KMS), Flowplayer, DataGrip, Pivotal Tracker, Slack, Sublime Text 2, Terminal, Litmus, AWS CloudFormation, AWS ECS, Chef, AWS ElastiCache, Vagrant, AWS OpsWorks, Cucumber, Pentaho Mondrian OLAP Engine

  • Paradigms

    Agile Software Development, REST, DRY, Object-oriented Design (OOD), Test-driven Development (TDD), Microservices, Scrum, Concurrent Programming, OLAP, Database Design, Parallel Programming, Distributed Programming, Software Testing, Microservices Architecture, HIPAA Compliance, Continuous Integration (CI), Continuous Deployment

  • Platforms

    OpenTok, Heroku, Twilio, Amazon Web Services (AWS), Linux, Twitter, Linode, WebSphere, OS X, Visual Studio Code, MacOS, IBM WebSphere, Docker, New Relic

  • Storage

    AWS S3, PostgreSQL, Redis, MySQL, Memcached, PL/SQL, Oracle RDBMS, Microsoft SQL Server, XML Schema, Sphinx Search Engine, Amazon Aurora, Elasticsearch, AWS RDS, MongoDB

  • Other

    Ruby Gems, System Architecture, RESTful Web Services, APIs, Fitbit, Cloudflare, Algorithms, Data Structures, Data Encryption, LDAP, Video Calling, Turbolinks, API Design, Delayed_job, CanCan, Shoulda, BEA AquaLogic Service Bus, CORBA, Stripe Webhooks, Stripe Sigma, Stripe Radar, Google Login, ActiveCampaign, iDevAffiliate API, Chrome Extensions, Pgcrypto, AWS, Pivotal Track, Artificial Intelligence (AI), Calculus, Algebra, Discrete Mathematics, Probability Theory, Statistics, Software Engineering, Neural Networks, Image Recognition, Speech Recognition, Data Compression, Data-level Security, ECMA, Highcharts Stock, Computer Science, Information Technology, AWS Route 53

Education

  • Master of Science degree in Computer Science
    2001 - 2006
    Warsaw University of Technology - Warsaw, Poland

To view more profiles

Join Toptal
Share it with others
Hire the top 3% of freelance developers TM