Hello, I'm Sergei Serafimovich.
After 20 years in building digital products, I’ve learned that the hardest part isn’t technology — it’s turning a vision into something real, usable, and loved by users. I help early-stage teams and founders close that gap — transforming ideas into scalable, market-ready products. My work blends product strategy, engineering, and design into a single process that moves fast without losing clarity. Whether I’m acting as a Fractional CPTO, founding engineer, or hands-on product developer, my goal is the same: to build high-quality software that stays true to the original vision. I stay close to the code and the craft, designing architectures, shaping user experiences, and guiding teams toward sustainable delivery. If you’re building something ambitious and need a partner who can bridge vision and execution — I’m open to a conversation.
Details
- Professional CategoryInformation Technology
- Location
- Years of Relevant Experience20+ years
- Seniority LevelC-Suite
- Consulting Rate (Hourly)185
Headline
Fractional CPTO
Experience
CPTO
ÆgteDecember 2022 - CurrentI partner with founders to bridge the difficult gap between a great idea and a real, market-ready product. My approach is built on a single point of accountable ownership, combining C-level strategy with the hands-on craft of building high-quality products.
Below are examples of my work embodying this philosophy.
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Engagement: Major E-commerce Retailer
(Jun 2024 - November 2024)
As a Principal Product & Technology Consultant, I led the development of a critical, customer-facing digital product for a major retailer with over 1,500 physical stores.
My role was to own the translation of complex business requirements into a high-performance, scalable e-commerce experience. I am responsible for the front-end architecture and work directly with stakeholders to ensure the final product delivers on key business goals for user engagement and conversion.
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Project: OctoSale (Founding Engagement)
(Jan 2023 - Present)
As the Founding Engineer & Product Lead, I led the end-to-end creation of Octo.Sale, a cloud-based sales and distribution platform. I was responsible for taking the project from a high-level concept to a fully functional product.
Key contributions included:
- Architecting the entire platform from the ground up to support a unified experience across mobile and web applications.
- Owning the complete product lifecycle, from initial concept and UX/UI design to hands-on front-end and back-end development.
- Developing the public API to enable seamless integration with third-party services.
Head of Product & Front-End Engineering
QantorJune 2017 - November 2022I led product and front-end engineering for QSale, a complex omni-channel E-Commerce platform. I drove the product from its early stages to a large-scale solution serving over 4 million monthly active users, 1,000+ stores, and processing more than 1 million orders.
My key contributions were focused on three areas:
Product & Team Leadership
I recruited, hired, and managed a cross-functional team of 10+ product managers, designers, and front-end engineers. I established the processes and culture that enabled us to build, launch, and scale a high-quality product in a complex business environment.
Product Ownership & Strategy
I owned the entire product lifecycle for QSale. This included conducting user research, defining the product roadmap, and translating high-level business goals into a clear, actionable vision for the technical and design teams.
Technical Leadership & Architecture
While leading the team, I remained deeply involved in the technical execution, guiding key architectural decisions and setting high standards for code quality and performance to ensure the platform could handle millions of users.
In addition to my core work on QSale, I also led a team to develop a complex Digital AIP (Aeronautical Information Publication) platform, where I was responsible for the API design, architecture, and front-end execution.
Head of UX/UI Development
OKPAYJune 2015 - June 2017As the Head of UX/UI Development for this international FinTech provider, I played a pivotal role in modernizing the company's core digital platforms, directly impacting both the customer experience and internal operational efficiency.
My role was to own the user experience strategy and execution across the product ecosystem. I was responsible for transforming our user-facing products into a more intuitive, modern, and effective suite of tools.
Key contributions included:
Product & Design Leadership
I provided the product and design leadership for the ground-up redesign of the company's most critical assets: the new client-facing payment portal and the internal back-office management panel. This involved navigating the complexities of a high-security FinTech environment to deliver a vastly improved user experience.
Team Development & Mentorship
I was responsible for mentoring and elevating the skills of the front-end and design team. I established and implemented best practices for UX design and development that significantly improved the quality, consistency, and usability of our products.
Corporate Website Initiative
In addition to the core products, I led the initiative to create the new corporate website, which served as the primary touchpoint for building trust with new customers and partners globally.
Industry
- Technology, Information and Media
Specific Jurisdictions That I'm Qualified In or Can Cover
Poland
Denmark
Germany
United Kingdom
United States
Austria
Netherlands
United Arab Emirates
Qatar
Portugal
Sweden
Norway
Estonia
Lithuania
Czech Republic
Serbia
Singapore
Canada
Belgium
France
Italy
Spain
Slovakia
Slovenia
Finland
Luxembourg
Switzerland
Latvia
Language(s)
- English
- Polish
- Russian
I am interested in
- Professional / Business Networking
- Career Opportunities
- Providing Services based on my Expertise