Nikolay Kazmin, Developer in Sofia, Bulgaria
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Nikolay Kazmin

Verified Expert  in Engineering

Software Developer

Sofia, Bulgaria
Toptal Member Since
December 29, 2020

Nikolay has a master's degree in computer science from ETH Zurich. He has more than ten years of full-stack web development experience. Before starting his own company, he worked as a contractor for one of the biggest brands in the US nonprofit sector—GuideStar. Nikolay's favorite technologies are Rails and React. He co-founded and led the technical development of Domestina: a marketplace for cleaning services with more than 100,000 booked cleanings.


Team Leadership, REST APIs, Back-end, Full-stack, SQL, HTML, Ruby, Leadership...
Back-end, Full-stack, SQL, HTML, Software Engineering, Databases, JavaScript...
Back-end, Full-stack, SQL, HTML, Ruby, Software Engineering, Databases...




Preferred Environment

GitHub, RubyMine, Windows 10

The most amazing...

...web app I've developed is Domestina ( It connects clients with cleaning companies and has more than 100,000 bookings to this date.

Work Experience

CTO and Co-founder

2013 - PRESENT
  • Created the software and database designs for the web app from scratch at the start of the company.
  • Led the implementation and continuous evolution of the web app using Ruby on Rails.
  • Enforced good practices in the development team which included mandatory tests, code reviews, code styling, CI, automated deployment with Capistrano, and server management with Ansible.
  • Recruited two other software engineers and trained them to become an integral part of the development team.
  • Led the transition of the front end from jQuery to React; also implemented the booking process with a complicated but very easy-to-use interface.
  • Integrated the Braintree payment system and developed automatic payments as well as an internal accounting/invoicing system both for Domestina and its contractor partners.
  • Integrated Viber messaging for instant communication with clients and partners.
  • Implemented a huge website redesign in 2019 using React more extensively as well as modern CSS features.
  • Helped with the product development by implementing "Jobs to be Done" interviews with clients and proposed numerous improvements to the product.
  • Created an admin interface for our contractor partners with Materialize CSS and Ruby on Rails.
Technologies: Team Leadership, REST APIs, Back-end, Full-stack, SQL, HTML, Ruby, Leadership, RubyMine, Software Engineering, Databases, JavaScript, CSS, Object-oriented Programming (OOP), Braintree API, Materialize, GitHub, MySQL, React, Ruby on Rails (RoR)

Senior Software Developer

2011 - 2015
  • Managed the technical part of the transition from Philanthropedia to GuideStar.
  • Developed the improved GuideStar's company profiles with Philanthropedia data.
  • Built integrations with third-party platforms including Salesforce.
  • Contributed to the development of the main website development using C# and ASP.NET MVC.
Technologies: Back-end, Full-stack, SQL, HTML, Software Engineering, Databases, JavaScript, CSS, Microsoft SQL Server, ASP.NET MVC, C#

Senior Software Developer

2009 - 2011
  • Developed the back end and front end of the website using Ruby on Rails, jQuery, and CSS.
  • Integrated PayPal payments and created an accounting system for the company.
  • Integrated Philanthropedia's data into GuideStar and oversaw the technical transition after Philantropedia was acquired.
Technologies: Back-end, Full-stack, SQL, HTML, Ruby, Software Engineering, Databases, Object-oriented Programming (OOP), MySQL, CSS, JavaScript, Ruby on Rails (RoR)

A marketplace where clients and cleaning companies meet. It has more than 100,000 bookings to this day. The web app automates everything including booking, payment, schedules, pricing, etc.

I started the project on day one and for the past two years, I have been the sole software engineer for all development activities.
2019 - 2020

Executive MBA (EMBA) in Business Administration

American University In Bulgaria - Blagoevgrad, Bulgaria

2008 - 2010

Master's Degree in Computer Science

ETH Zurich - Zurich, Switzerland

2005 - 2008

Bachelor's Degree in Computer Science

Jacobs University Bremen - Bremen, Germany


Braintree API, React, REST APIs


RubyMine, RSpec, GitHub


Ruby on Rails (RoR), Bootstrap, Materialize, ASP.NET MVC


CSS, Ruby, HTML, SQL, JavaScript, C#


Object-oriented Programming (OOP)


MySQL, Databases, PostgreSQL, Microsoft SQL Server


Software Engineering, Full-stack, Back-end, Team Leadership, Presentations, Finance, Strategy, Negotiation, Leadership

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