Roman Semko Androsenko, Developer in Leipzig, Saxony, Germany
Roman is available for hire
Hire Roman

Roman Semko Androsenko

Verified Expert  in Engineering

Full-stack Developer

Leipzig, Saxony, Germany
Toptal Member Since
May 5, 2020

Roman has over a decade of experience excelling as a web, blockchain, and mobile developer. With a solid financial background and 20+ years of excellence in IT, he brings a unique blend of skills to clients, especially in the B2B domain. He won Samsung's mobile development challenge and has seen his apps used by millions. Roman founded two successful startups and has played a crucial role as CTO and solutions architect in several projects.


Hexgo inc.
Solidity, Web3.js, Blockchain, React, Non-fungible Tokens (NFT), Next.js...
Digitalia Publishing Corp
Architecture, Blockchain, Amazon, Amazon Web Services (AWS), AWS Lambda...
GAT Network
Web3.js, Solidity, Ethereum




Preferred Environment

Visual Studio Code (VS Code), MacOS, Blockchain, Web3.js, Ethereum, React

The most amazing...

...product I've built is a Web3 startup that won the Binance Labs Incubation Program among 3,000+ applicants.

Work Experience

Smart-contract Blockchain Developer

2022 - 2022
Hexgo inc.
  • Sketched and designed a working solution for an NFT smart contract.
  • Helped the client through all the conception, testing, and deployment stages.
  • Tested and adapted the Next.js-based minting page.
Technologies: Solidity, Web3.js, Blockchain, React, Non-fungible Tokens (NFT), Next.js, Node.js, Hardhat, Alchemy, OpenZeppelin, Vercel, GitHub, Blockchain Design

CTO | Lead Engineer

2022 - 2022
Digitalia Publishing Corp
  • Developed architecture and roadmap for a complex three-token project with fungible and non-fungible assets.
  • Managed a team of developers and designers to get the job done.
  • Completed a working MVP and deployed it to a live chain.
Technologies: Architecture, Blockchain, Amazon, Amazon Web Services (AWS), AWS Lambda, Web3.js, Ethers.js, Ethereum

Founder and Developer

2020 - 2022
GAT Network
  • Launched an NFT-based game (GameFi) on Binance Smart Chain.
  • Created a multi-network, flexible anything-for-anything trading platform.
  • Participated in the Binance Incubation Program as one of the finalists.
Technologies: Web3.js, Solidity, Ethereum

Senior Front-end Developer

2020 - 2020
Jalesh Cruises Mauritius, Ltd.
  • Planned front-end architecture, including the structure of repositories, technology selection, and components hierarchy.
  • Implemented a mobile website for the cruise company, including fully functional cruise searching, selection, and booking flows.
  • Set up Docker deployment for posterior DevOps integration.
Technologies: Figma, SCSS, CSS3, HTML5, Docker, GraphQL, Next.js, React

Senior Full-stack Developer

2020 - 2020
  • Created a GraphQL enabled Node.js (FeathersJS) back end and connected it with various upstream APIs and data sources (MySQL, MongoDB, REST) for a fintech company in the mortgage rates aggregation industry.
  • Created a Tableau dashboard for optimal data visualization and further analysis.
  • Delivered pluggable web components with Vue.js, TypeScript, and a beautiful interface with SASS to present easy-to-read rates to the end user.
  • Utilized Docker and Docker-Compose to deploy the solution. Worked remotely in a distributed team with scrum.
Technologies: MySQL, MongoDB, REST APIs, RESTful Development, Business Intelligence (BI), Tableau, Material Design, FeathersJS, GraphQL, TypeScript, Node.js

Full-stack Developer

2020 - 2020
Sportsbook Cloud
  • Assisted on a legacy Python/Django platform for a highly scalable, real-time betting platform.
  • Developed the Socket.IO communication further, between the RabbitMQ-enabled back end and the front end.
  • Utilized CSS modules and React with Typescript to create a user control panel.
  • Integrated an upstream Betradar API based on REST and AQMP.
  • Created Docker containers for Logstash , connecting it to Elasticsearch.
  • Deployed the solution with Docker/Kubernetes to Google Cloud (integrated GitLab CI/CD). Worked on Kibana reports and dashboards.
  • Split the legacy platform into lean microservices with more focus on the Django Rest framework instead of sockets and separation of concerns.
  • Cleaned the legacy PostgreSQL database. Worked in an agile, distributed team with scrum.
Technologies: Socket.IO, Celery, Betradar, RabbitMQ, Kubernetes, Logstash, Elasticsearch, Python, React, Django

Senior Full-stack Developer

2019 - 2020
  • Maintained a legacy monolith platform built in PHP and a custom jQuery framework for a biggest German travel portal in an agile multi-team environment.
  • Reverse-engineered the legacy platform, documented the lost know-how and secured it with new unit and E2E tests.
  • Introduced the Cypress test suite. Consulted QA regarding test tool selection.
  • Implemented the new travel platform based on microservices, written with Node.js and Golang.
  • Implemented the new, lean, mobile-first front end written in React.js.
  • Collaborated with UX/UI to create a breath-taking component library in Figma and implemented it with React.
  • Added Zendesk channels to route tickets from the legacy support platform.
  • Built the interface for a Zendesk app to quickly report a bug via Jira from Zendesk ticket interface.
  • Added new features to the legacy platform with step-wise integration of React components.
  • Worked with GitLab CI/CD pipelines to build, test, and deploy the solution to AWS.
  • Added tracking code for Google analytics in the old and the new platforms.
Technologies: Amazon Web Services (AWS), Google Tag Manager, Google Analytics, Storybook, Elasticsearch, REST APIs, Docker, Continuous Delivery (CD), Continuous Integration (CI), Node.js, Jest, Cypress, Go, TypeScript

Project Lead

2019 - 2019
  • Worked on a proof-of-concept solution for the biggest German gas infrastructure provider to create distributed market based on DLT and a way to certify the usage of green/clean energy.
  • Created a lean MVP for the patented consensus technology written in Node.js.
  • Built a physical city model with gas infrastructure and a set of Raspberry PIs running Linux and communicating over WiFi in a mesh network.
  • Connected control panels with displays running an Angular dashboards to control the Raspberry PIs.
  • Organized the event to present the proof-of-concept solution to the company's board of directors.
Technologies: Cryptocurrency, Socket.IO, Angular, Raspberry Pi, JavaScript, TypeScript, Node.js

Senior Front-end Developer

2018 - 2019
  • Worked with scrum in an agile, distributed, multi-team environment for the largest European B2B marketplace.
  • Assisted the user authentication team to integrate Auth0 and OAuth 2 authentication using AWS Lambda.
  • Aided in the writing of Terraform scripts for microservice infrastructure deployment to AWS.
  • Collaborated with the front-end team. Created a next-generation user interface for the marketplace with React and TypeScript.
  • Created a component library for the new interface with React and Styled Components.
  • Coached the UI team in tools selection and better workflow with developers.
Technologies: Amazon Web Services (AWS), Storybook, Terraform, PostCSS, OAuth 2, JSON Web Tokens (JWT), MobX, Cypress, Node.js, JavaScript, TypeScript, React

Developer | Inventor | Founder

2016 - 2019
  • Developed a distributed auto-peering software that was used by over 80% of IOTA nodes worldwide.
  • Designed and patented a distributed, accessible, messaging network (DAMN) to ensure consistency and consensus in unstable and highly malicious environments.
  • Created beautiful dashboards with Bootstrap to control and visualise node connections within a network.
  • Utilized gRPC and Golang, created a lighting-fast, lean node software able to run on Raspberry Pi Zero.
  • Developed a PoC cryptocurrency ledger based on the patented consensus technology.
  • Created a cross-platform desktop node software with Electron.
Technologies: IOTA, Cryptocurrency, Blockchain, Raspberry Pi, RPC, gRPC, Electron, Express.js, Go, Python

Senior Front-end Developer

2016 - 2018
TomTom Telematics
  • Developed a fleet management platform for B2B customers in a vast, multi-team project using React/Redux.
  • Created fleet visualization using Google Maps API and Leaflet.
  • Collaborated with the software architect to create an integrated test framework, combining Unit, UI, and E2E tests, and all their coverage data into a single reporting tool.
  • Reverse-engineered the predecessor legacy platform to add new features to the new web fleet solution.
  • Adapted webpack heavily, creating plugins for the required complex build and deployment process.
  • Added Google Analytics tracking for feature usage reports.
Technologies: Google Analytics, Leaflet, Reverse Engineering, PostgreSQL, Cucumber, Gherkin, Selenium, TypeScript, JavaScript, ECMAScript (ES6)

Front-end Developer

2015 - 2016
Zippel Media, GmbH.
  • Performed as a front-end developer for a marketing media creation company.
  • Designed SaaS in Angular, where users could upload and edit media content for marketing purposes.
  • Integrated the solution with Facebook API for one-click ads posting using the media from the gallery.
  • Collaborated with the CTO and CEO to estimate and create an MVP. Worked in an agile, distributed team with scrum.
Technologies: Facebook API, Azure, Agile, Scrum, CSS, Material Design, AngularJS, JavaScript

Project Lead

2014 - 2016
  • Estimated, planned, and executed two large projects related to user psychology and marketing.
  • Wrote user management and complex roles for solution sub-licensing, invoicing, and other back-office tools in Django (Django REST Framework).
  • Used the Django REST framework to develop a flexible API for future use-cases.
  • Assisted in the design and build of user interfaces for questionnaires and the 3D visualization of reports.
  • Analyzed data and stored it for further use and visualization with Pandas and scikit-learn.
  • Developed AI components based on research papers that were used to evaluate the questionnaire's data.
Technologies: Amazon Web Services (AWS), Data Visualization, Software Architecture, OAuth 2, Azure, Scikit-learn, Pandas, Django, MySQL

Project Lead

2013 - 2016
  • Estimated and led a wide range of proof-of-concept websites, ranging from simple questionnaires up to AI-enabled recommendation engines and high-traffic video sites.
  • Implemented PoC projects in a wide range of front-end and back-end technologies.
  • Deployed and maintained the projects in auto-scalable setups (DevOps) on AWS and Google App Engine.
  • Implemented Google Analytics to track usage.
Technologies: Google Analytics, Ubuntu Server, Streaming, Facebook API, OAuth 2, AngularJS, Node.js, Django, Python

Project Lead

2012 - 2016
Nutrivital Health Group
  • Estimated and planned further development of an abandoned, unfinished back-office solution for client management, inventory, invoicing, shop, and the scheduling of medical staff.
  • Used Django to create a flexible, powerful backoffice solution.
  • Further developed and maintained the user front end written with jQuery. Set up and maintained the PostgreSQL server.
  • Built reporting tools with Pandas, including its visualization on the front end.
  • Added an invoicing module to generate invoices in PDF format and automatically send them using AWS SES.
  • Scheduled back office jobs with Amazon SQS and Celery.
Technologies: Celery, Pandas, Business Intelligence (BI), Memcached, PostgreSQL, Python, jQuery, Django

Front-end Developer

2012 - 2013
  • Acted as the front-end developer in one of the biggest credit portals in Germany.
  • Created questionnaire strips with highly customized Bootstrap and jQuery (UI).
  • Assisted with the REST interface built in PHP. Worked on a solution to make the questionnaire strip while-label with flexible templating and configuration.
Technologies: Bootstrap, Templating, Sass, CSS, REST, PHP, jQuery


2010 - 2012
Nails Finder
  • Founded the biggest German-speaking social platform for professional nail designers.
  • Developed the back end, databases, deployment, auto-scaling, and CDN to ensure everything worked smoothly.
  • Sold the startup to the largest nail and beauty company in Germany.
  • Developed the front end to create a stunning SPA before it became popular.
  • Participated in the whole life-cycle of the startup from idea to exit.
  • Implemented Google Analytics to track usage.
Technologies: Google Analytics, REST, GitLab CI/CD, jQuery, Autoscaling, PostgreSQL, Java, Python

Web and Mobile Developer

2007 - 2012
  • Developed a large set of Android apps during the early years of Android's existence. One app was one of the top-3 most downloaded during a long period of time with over three million users.
  • Ran the biggest developer community "BadaDev" for the Samsung's Bada mobile platform.
  • Developed 20+ apps for Samsung in C++ to fill their app store.
  • Designed an Android app for one of the largest car magazines worldwide, the South African CarMag.
  • Participated and won Samsung's mobile development challenge.
  • Collaborated with Tunewiki, the winner of Android's development challenge, to port their player to Bada.
  • Created a game for Tunewiki on Android using OpenGL. Ported the same game to Bada.
  • Developed many different web and CMS projects with WordPress and Joomla, designed the interfaces, maintained projects, and managed hosting.
  • Developed a WordPress-based real-estate management system for a Spanish real-estate company.
Technologies: JavaScript, CSS, HTML, WordPress, PHP, OpenGL, C++, Bada, Android, Java

Bridgestone Webfleet
A React-based telematics solution to manage vast fleets of vehicles. I worked as a front-end developer, and closely with the back-end developer, UI/UX team, product owner, and project manager to create an amazing product.

Invia Travel Portal

This is one of the biggest travel portals in German-speaking countries. I maintained their legacy system. It ran on PHP and a custom jQuery framework. I also developed their next-generation platform built with React in the front end and lean GoLang/Node.js microservices.

This is the biggest B2B marketplace in Europe. I was working as a front-end developer and as back-end support to create a next-generation platform to replace their legacy monolith solution. We deployed to AWS with Terraform.

Sofistiq rep:grid
Together with my team, we created a marketing analysis tool with an AI-enabled back end and 3D visualization of data on the front end using AngularJS and D3.js. My job was to estimate the project, design the graphical interface, implement the AI on the back end, and develop the visualization and project/client management interfaces. I also created the video presentation using Adobe After Effects.

Sofistiq Cube
Together with a small team, we created a behavioral analysis tool that helps one measure and visualize a person's behavior patterns and portrays connections, dependencies, and influences in a multi-dimensional space. My job was to estimate the project, plan the implementation, create the back-office with client management, create automatic invoicing and technology sub-licensing to certified partners, and create a user control panel and a flexible questionnaire system on the front end.

Sportsbookcloud - Aleatech
I developed a highly-scalable, high-performance white-label online, and PoS betting platform. My primary responsibility was to redesign the old monolith into a lean microservice architecture and develop the user area (profile) views.


Designed and patented a distributed, accessible, messaging network to ensure consistency and consensus in unstable and highly malicious environments. Developed a PoC cyptocurrency ledger based on the patented consensus technology.

Worked with the Finanzcheck team to create a flexible, white-label questionnaire strip for user data collection and the posterior presentation of fitting offers. Assisted in tools and frameworks selection for the task and developed the PHP API.

Founded the biggest German-speaking social platform for professional nail designers with thousands of users. Completed the whole startup lifecycle from conceptualisation, planning, prototyping, financing, development and posterior exit. Sold the company to the biggest German nail design supplies manufacturer and retailer.

This is a large German agency offering digital transformation solutions to its clients. I worked on many different proof-of-concept projects, usually completing the entire software development cycle from estimating, consulting, planning, implementation to feedback tracking. A wide variety of technologies and requirements were utilized. We built small landing pages up to high-traffic solutions for clients like McDonald's.
2008 - 2009

Bachelor's Degree in Computer Science

Technical University of Darmstadt - Darmstadt, Germany

2004 - 2006

Diploma in Finance and Economics

Feda EDU (Previously ASET - German Business School) - Madrid, Spain

2000 - 2002

Diploma in Computer Science

Hamburg Fernakademie (Technical College) - Hamburg, Germany


Machine Learning

Stanford University


License in Road Transportation/Logistics Management

Spanish Ministry of Transportation


Django ORM, REST APIs, React, MobX, Node.js, jQuery, jQuery UI, Web3.js, Zendesk API, Scikit-learn, Pandas, WebRTC, Plaid API, Socket.IO, Auth0 API, Leaflet, D3.js, WebGL, Facebook API, OpenGL, Vue, Vue 2, Vuex, OpenZeppelin


JSX, Docker Compose, Confluence, PostCSS, Webpack, GitLab, Git, AWS ELB, Kibana, Logstash, Plaid, Tableau, Celery, Jenkins, Figma, Auth0, Cucumber, Google Analytics, IntelliJ IDEA, Vim Text Editor, Zsh, React Apollo, GitLab CI/CD, Terraform, GitHub, Amazon EBS, Amazon Simple Email Service (SES), Amazon Simple Notification Service (Amazon SNS), RabbitMQ


Django, gRPC, Cypress, Jest, Django REST Framework, Redux, Material UI, Express.js, FeathersJS, Bootstrap 3, Selenium, Next.js, Bootstrap, Flask, AngularJS, Angular, Electron, JSON Web Tokens (JWT), OAuth 2, Tailwind CSS, Hardhat, Alchemy


Python 2, Python 3, Sass, Python, ECMAScript (ES6), CSS, SCSS, HTML5, HTML, JavaScript, JavaScript 5, JavaScript 6, CSS3, CSS4, Go, TypeScript, Solidity, PHP, Gherkin, Java, C++, GraphQL


RESTful Development, REST, Scrum, HTML DOM, Modular CSS, Microservices, Microservices Architecture, Distributed Computing, Business Intelligence (BI), Continuous Integration (CI), Continuous Delivery (CD), Templating, Agile


Elasticsearch, MySQL, Redis, Amazon S3 (AWS S3), MongoDB, Google Cloud, Memcached, PostgreSQL


Amazon EC2, Raspberry Pi, Linux, Ubuntu, Ubuntu Linux, Amazon Web Services (AWS), Docker, Blockchain, Ethereum, Google App Engine, Zendesk, Google Cloud SDK, Raspberry Pi 3 GPIO, Arch Linux, AWS Lambda, Heroku, MacOS, Azure, Android, WordPress, Kubernetes, Amazon, Vercel, Visual Studio Code (VS Code)


APIs, Component Libraries, Software Architecture, Reverse Engineering, Ubuntu Server, IT Projects, Minimum Viable Product (MVP), Consensus Algorithms, Ethers.js, Styled-components, CSS Grid, Django-rest-auth, Data Visualization, Data Analysis, TSLint, Project Lifecycle, Project Planning, Large-scale Projects, RPC, Material Design, Non-fungible Tokens (NFT), Smart Contracts, Ethereum Smart Contracts, Trading, Machine Learning, Distributed Systems, Distributed Ledgers, Distributed Messaging, Cryptocurrency, IOTA, Crypto, RESTful Microservices, Web Components, Video Streaming, Streaming, SAP, Startups, Autoscaling, Google Tag Manager, Gatsby, Affinity Software, Storybook, Bada, Betradar, Serverless, Architecture, Blockchain Design, Algorithmic Trading

Collaboration That Works

How to Work with Toptal

Toptal matches you directly with global industry experts from our network in hours—not weeks or months.


Share your needs

Discuss your requirements and refine your scope in a call with a Toptal domain expert.

Choose your talent

Get a short list of expertly matched talent within 24 hours to review, interview, and choose from.

Start your risk-free talent trial

Work with your chosen talent on a trial basis for up to two weeks. Pay only if you decide to hire them.

Top talent is in high demand.

Start hiring