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 thirteen 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 nine years.
Mateusz is now available for hire




Warsaw, Poland



Preferred Environment

OS X, Sublime Text 3, GitHub, iTerm

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.


  • 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 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, Resque, PostrgreSQL, Pgcrypto, RSpec, Capybara, AWS S3, AWS KMS, AWS SNS, AWS SES, AWS Elasticsearch, AWS CloudFront, Redis, OpenTok API, Pusher API, FlowPlayer API, SemaphoreCI, NewRelic, jQuery, Haml, Sass, CSS3, Bootstrap 2/3
  • 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, CoffeeScript, jQuery, Haml, HTML5, Sass, CSS3, Twitter Bootstrap, Sidekiq, PostgreSQL, RSpec, Capybara, Selenium Webdriver, BackboneJS, AWS S3, AWS CloudFront, Redis, Heroku, Twilio API, 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: Ruby on Rails, CoffeeScript, jQuery, Haml, HTML5, Sass, CSS3, Twitter Bootstrap, Delayed::Job, PostgreSQL, MySQL, RSpec, Capybara, Selenium Webdriver, Twilio API, Facebook API, Twitter API, Linode, CloudFlare, 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 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, jRuby, Ruby, CoffeeScript, jQuery, BackboneJS, RaphaelJS, HTML5, Haml, CSS3, Sass, Twitter Bootstrap, OLAP, Pentaho Mondrian
  • 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, JavaScript, HTML, CSS, Delayed::Job, CanCan, Haml, Liquid, Airbrake, Capistrano, Shoulda, Factory Girl, Clearance, Paperclip, Nokogiri, Will Paginate
  • Ruby on Rails Developer

    2010 - 2010
    Netronix, Inc.
    • Developed a web application for remote monitoring of environmental data (e.g., weather, wind, water quality, temperature, flow, or depth).
    • Led the transition of a beta product to production state with its first paying customers.
    • Created a multi-threaded Ruby server listening for measurements data sent by remote sensors over Iridium Satellite. The costly satellite bandwidth required 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 (e.g., water depth at node y > x).
    Technologies: Ruby on Rails, HTML, Sass, CSS, JavaScript, HighCharts, Prototype.js, 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, MySQL, HTML, CSS, JavaScript, jQuery
  • J2EE Designer and Developer

    2007 - 2008
    • 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).
    • Utilized Agile methods in programming.
    Technologies: J2EE, IBM WebSphere Business Modeler, WebSphere Integration Developer, WebSphere Process Server, Eclipse RCP, Eclipse Modeling Framework, 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: J2EE, Eclipse RCP, jUnit, Spring, BEA AquaLogic BPM, XML, Castor, DOM API
  • J2EE, PL/SQL Developer

    2004 - 2006
    • 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.
    • Designed a relational database.
    • Analyzed business workflows and prepared functional and technical specifications in waterfall methodology.
    • Organized training for new users.
    Technologies: PL/SQL, Oracle RDBMS, MS SQL Server, J2EE, Apache Torque/Turbine/Velocity, HTML, CSS, JavaScript


  • Diagnotes (Development)

    A web application for secure healthcare communication.

  • OK Venue (Development)

    A web application for creating events and selling tickets.

  • InstantCashSweepstakes (Development)

    A web application for online surveys coupled with online market research web application

  • Environet (Development)

    A web application for remote monitoring in the environment sector.

  • Utilizing Agent Teams in Grid Resource Brokering (Scientific Paper) (Other amazing things)

    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 (Scientific Paper) (Other amazing things)

    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 (scientific paper) (Other amazing things)

    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 — Preliminary Considerations (Scientific Paper) (Other amazing things)

    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.


  • Languages

    Ruby, HTML, SQL, HTML5, Sass, CoffeeScript, CSS3, Haml, CSS, JavaScript, SAML, Java, TypeScript 2, TypeScript, ECMAScript (ES6)
  • Frameworks

    Ruby on Rails (RoR), Capybara, Bootstrap, Swagger, OAuth 2, minitest, AngularJS, Angular
  • Libraries/APIs

    Pusher, API Development, Resque, Ruby on Rails API, Nokogiri, CarrierWave, Devise, Highcharts, jQuery, Sidekiq, Stripe, PubNub, Twilio API, Braintree API, Selenium WebDriver, OmniAuth, Backbone.js, Moment.js, React, D3.js, Google Maps, Paperclip, Facebook API, Mandrill API, Mongoid, Twitter API, PayPal API
  • Tools

    Git Flow, SemaphoreCI, GitHub, RSpec, AWS SDK, Rubocop, AWS Push Notification Service (AWS SNS), AWS SES, Capistrano, Git, 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), Scrum, Concurrent Programming, Microservices Architecture, HIPAA Compliance, Continuous Integration (CI), Continuous Deployment
  • Platforms

    OpenTok, Heroku, Twilio, Amazon Web Services (AWS), Linux, Docker, New Relic
  • Storage

    AWS S3, PostgreSQL, Redis, MySQL, AWS RDS, MongoDB
  • Other

    System Architecture, RESTful Web Services, APIs, Fitbit, Data Encryption, LDAP, Video Calling, Turbolinks, API Design, AWS Route 53


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

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