Sergey Moiseev, Full-stack Developer in Tallinn, Estonia
Sergey Moiseev

Full-stack Developer in Tallinn, Estonia

Member since May 9, 2014
Sergey is a full-stack software engineer with experience developing complex web projects. He has extensive skills as an analyst and with gathering requirements for project development. He boasts practical experience in all levels of participation from full-stack developer to team lead/CTO. He is a top 5% answerer for AngularJS on StackOverflow, and top 10% on Ruby on Rails.
Sergey is now available for hire




Tallinn, Estonia



Preferred Environment

Angular, Ruby on Rails (RoR), Ruby

The most amazing...

...things I've done are migrations for projects of different kinds to newer frameworks and architectures, making them respond to business needs faster.


  • Full-stack Developer

    2018 - 2022
    Ygrene Energy Fund (Toptal Client)
    • Aided in creating a new prequalification and application process with Angular 6 and NgRx.
    • Helped create a monorepo layout for Angular apps, using NX, NGRX, shared modules, and environment to deliver new front-end projects quickly and efficiently.
    • Created a supporting proxy-like module for a new application process back end to provide new workflows in an existing feature-flag-based process without additional data models using Rails.
    • Supported an automated underwriting system implementation by covering all key Ruby code, making it reliable and maintainable.
    • Implemented the initial message bus encryption mechanism for securing microservice interoperation, using Ruby and AWS SQS.
    • Migrated multiple services from Scala to Ruby, using Scala code as a source of requirements. They include external postal providers, environment management solutions (backup scrubbing and event-based S3 archival solutions), and GIS-based solutions.
    • Helped maintain and improve automatic microservice client generation, using the zero-rails_openapi gem and open API generator.
    • Built a new system area configuration service using a Hotwire (Turbo) Ruby on Rails 7 architecture.
    Technologies: Amazon Web Services (AWS), Redux, RESTful Web Services, Angular Material, NgRx, Swagger, Docker, Scala, Kubernetes, Ruby on Rails (RoR), Ruby, Angular, SAML, Turbo, Hotwire, Material Design, TypeScript, Ruby on Rails 7
  • Full-stack Web Developer

    2017 - 2018
    Caspar Health (via Toptal)
    • Created a front-end application for the main business platform utilizing Angular 5 and Ngrx.
    • Helped release a product that made one of five finalists at Disrupt Berlin Startup Battlefield 2017.
    • Aided the refactoring and developing of the Ruby on Rails application back end.
    Technologies: Amazon Web Services (AWS), Ruby on Rails 5, Redux, RESTful Web Services, Angular Material, NgRx, Docker, PostgreSQL, Angular
  • Full-stack Web Developer

    2017 - 2017
    Everwill (via Toptal)
    • Set up and moved an AWS Elastic Beanstalk Multicontainer Docker configuration to production.
    • Built a new version of the company's main application on Angular 4.
    • Implemented a flexible workflow engine for the application.
    Technologies: Redux, RESTful Web Services, NgRx, AWS Elastic Beanstalk, Docker, MongoDB, Ruby on Rails (RoR), Ruby, Angular
  • Full-stack Web Developer

    2014 - 2017
    International Technological University (via Toptal)
    • Implemented ITU Bridge—a project to help students and alumni to apply for jobs at top companies.
    • Implemented ITU's single sign-on solution, the ITU ID.
    • Implemented ITU Student Relationship Management, a system for automating admissions data and documents collection process. The system included Stripe and SalesForce integrations.
    • Worked as a back-end Rails developer, an AngularJS front-end developer, and DevOps for all mentioned projects.
    Technologies: Ruby on Rails 5, Redux, RESTful Web Services, Angular Material, MySQL, CSS3, HTML5, AngularJS, Ruby on Rails (RoR), Ruby
  • CTO

    2013 - 2014
    Information Ideas
    • Implemented a production-ready SPA job search site.
    • Formed a team of two developers to work on a project.
    • Built a set of AngularJS directives for competence tree rendering and selection.
    • Created a competence search engine on top of Redis.
    • Created a complex UI with interacting controls on top of AngularJS.
    Technologies: Ruby on Rails 5, RESTful Web Services, AngularJS, Redis, PostgreSQL, Ruby on Rails (RoR)
  • Development Team Lead

    2012 - 2013
    HeadHunter Group
    • Implemented an online competence-based candidate search project in a small team of three developers.
    • Provided a full cycle of requirements analysis for the project.
    • Implemented property search on top of a Redis set intersection.
    • Built a RIA interface for a project using Backbone.js.
    • Created an automated competence pre-fill solution using candidate resumes as the data source.
    Technologies: RESTful Web Services, Backbone.js, Redis, PostgreSQL, Ruby on Rails (RoR)
  • CTO

    2011 - 2012
    KupiKupon Global
    • Supported a high-load production environment for a daily deal site on top of Drupal.
    • Managed and implemented a new version of a site using Ruby on Rails.
    • Migrated all data to a new project and replaced the old project with the new one.
    • Formed a development team of ten developers by putting together position requirements, interviewing, and training.
    • Implemented a VoIP call center solution based on Asterisk PBX.
    Technologies: RESTful Web Services, PostgreSQL, Ruby on Rails (RoR)
  • CTO

    2008 - 2011
    Digital Distribution Center
    • Formed a team and started an internal software development process in the company.
    • Moved an outsourced project with the support of a formed team and completed its development from early prototype to production-ready version.
    • Managed a complete rewrite of the project from PHP to Ruby on Rails.
    • Created an in-house digital right management solution for the project.
    • Applied Agile practices to the working process and set up a development cycle for the company.
    Technologies: RESTful Web Services, VMware, Flex, Flash, PHP, PostgreSQL, Ruby on Rails (RoR)
  • Lead Developer | System Analyst | Head of R&D

    2004 - 2008
    Chronopay B.V.
    • Implemented integrations with Parex (, UCS (, and other payment providers.
    • Developed many improvements to the Chronopay PSP system. Included many new architectural improvements, integration processing, 3D secure implementation, and more.
    • Applied Agile practices in the working process and set up the development cycle for the company.
    • Provided analytical support for the work cycle of the R&D department. Provided a full cycle of business analysis for the company.
    • Provided support for three annual PCI DSS certifications.
    Technologies: Mono, PostgreSQL, PHP
  • Lead SW Developer

    2000 - 2001
    • Developed (currently unavailable) from base technical requirements to the product in use.
    • Managed a team of three developers in the process of developing
    • Developed modules for the Ayaxi main product ­Ayaxi Publisher, used in client installations.
    • Provided development analysis for the early stages of the president of Russia website [].
    • Developed methods for outsourcing work support, code format requirements, and documentation format guides.
    Technologies: Microsoft SQL Server, ASP


  • - Russian E-library

    I managed this project and wrote a large amount of its code.

  • Everwill

    Everwill Online Wizard experience was implemented using Angular 4 and Twitter Bootstrap 4. It's a responsive mobile first application with rich user interface.

  • An Angular 5 Tutorial: Step by Step Guide to Your First Angular 5 App (Publication)
    Angular 5 is a new version of the Angular framework developed by Google. Angular 5 comes with improvements including optimized builds and faster compile times, but in this Angular 5 tutorial, we are going to build a notes app from scratch. If you’ve been waiting to learn Angular 5, this tutorial is for you.


  • Languages

    Ruby, UML, Sass, CSS3, Haml, CoffeeScript, HTML5, JavaScript, SQL-99, PHP, Scala, SAML, TypeScript
  • Frameworks

    Angular, Ruby on Rails (RoR), AngularJS, Angular Material, Slim, Factory Girl, Bootstrap, Swagger, ASP, Mono, Flex, Ruby on Rails 5, Protractor, Redux
  • Libraries/APIs

    Devise, REST APIs, NgRx, Pundit, Stripe API, Salesforce API, Sidekiq, AngularUI, jQuery, Restangular, Backbone.js
  • Paradigms

    RESTful Development
  • Platforms

    Docker, Linux, AWS Elastic Beanstalk, Amazon Web Services (AWS), MacOS, Windows, Kubernetes
  • Storage

    PostgreSQL, MySQL, Redis, Microsoft SQL Server, MongoDB
  • Other

    State Machines, RESTful Web Services, Puma, ISO 8583, GitFlow, Hotwire, Material Design, Ruby on Rails 7
  • Tools

    NGINX, Git, RSpec, Capistrano, Flash, VMware, Turbo


  • Master's Degree in Computer Engineering
    1995 - 2001
    Moscow State Institute of Electronics and Mathematics (Technical University) - Moscow, Russia

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