Denys N., Full-Stack Developer

Work experience

Senior Full-Stack Engineer, NDA Company

Duration: Dec. 2024 - Present

Summary: Building a secure and scalable online casino SaaS platform offering real-money and social games. Focused on developing robust APIs, third-party payment integrations, real-time session management, and a responsive UI.

Key Responsibilities:

• Designed and maintained secure REST APIs with Express.js for game and user management;
• Integrated Stripe for payment handling and implemented user authentication with Google Auth;
• Built WebSocket-based real-time game logic and session state features;
• Collaborated on UI/UX design for a responsive user interface;
• Implemented promotional and loyalty systems based on user behavior patterns.

Technologies: Express.js, PostgreSQL, Docker, RainbowKit, Crossmint, RESTful API, Stripe, AWS, Google Auth, WebSockets, Microservices.

Senior Full-Stack Mobile Engineer, Fit.AI - Ultra Personal Fitness App

Duration: Jan. 2024 - Dec. 2024

Summary: Fit.AI: Ultra Personal Fitness is an AI-powered fitness app designed to deliver highly personalized workout plans tailored to individual fitness levels, goals, and preferences. It features a 24/7 AI coach that provides guidance and motivation, structured 4-week workout cycles, and social functionalities allowing users to connect and stay accountable with friends.Additional features include daily fitness articles, progress tracking, and integration with Apple Health, all within a user-friendly interface.

Key Responsibilities:

• Built mobile app using React Native and Expo for both iOS and Android;
• Developed AI-based workout cycle logic and personalized coaching workflows;
• Integrated Apple Health for fitness data and Stripe for payment handling;
• Ensured real-time interactivity using WebSockets and managed app state via Redux Toolkit and Zustand.

Technologies: JavaScript, TypeScript, React Native, Expo, Zustand, Redux Toolkit, Node.js, Nest.js, PostgreSQL, Stripe, AWS, Apple Auth, WebSockets.

Senior Full-Stack Engineer, AI Salesforce SaaS Platform

Duration: Oct. 2023 - Aug. 2024

Summary: The SalesForce Artificial Intelligence site showcases Salesforce's artificial intelligence (AI) solutions integrated into their platform to improve business processes. It provides information about tools such as Agentforce and Einstein that help automate tasks, increase productivity, and personalize customer interactions.

Key Responsibilities:

• Developed reusable front-end components with React and Material UI;
• Integrated OpenAI APIs for intelligent workflows;
• Built secure back-end with Nest.js and MongoDB, with both REST and GraphQL APIs;
• Designed headless CMS integration and implemented Stripe billing logic.

Technologies: TypeScript, JavaScript, React, Material UI, Redux, OpenAI API, Node.js, Nest.js, GraphQL, Stripe, MongoDB, Google Cloud, Jest.

Middle Full-Stack Mobile Engineer, CBS Sports Mobile App

Duration: Nov. 2022 - Oct. 2023

Summary: CBS Sports App is a mobile app for sports fans that provides real‑time scores, news, analytics, and live streams.

Key Responsibilities:

• Built mobile UI with React Native and enhanced user interactions;
• Integrated backend APIs with Express.js, improving data flow and response speed;
• Implemented JWT Auth, Redis caching, and performance enhancements;
• Managed secure payment workflows with Stripe and GraphQL APIs.

Technologies: JavaScript, TypeScript, React Native, Expo, Node.js, Express.js, Stripe, AWS, PostgreSQL, Tailwind CSS, Redis, JWT, GraphQL, WebSockets.

Middle Full-Stack Engineer, E-commerce Platform - Staff-Clothes

Duration: Jan. 2022 - Nov. 2022

Summary: Staff-Clothes is an e-commerce platform that specialises in corporate clothing for businesses in various industries.

Key Responsibilities:

• Developed product and order management back-end logic in Node.js;
• Built user-friendly interfaces using Next.js and integrated payment systems with Stripe;
• Managed content with Sanity CMS and maintained responsive design with ShadCN components.

Technologies: React, Next.js, Redux, ShadCN, Stripe API, Node.js, Express.js, Sanity CMS, MongoDB, Google Cloud Platform, Redis.

Middle Full-Stack Engineer, BananaHome - E-commerce Furniture Platform

Duration: May 2021 - Dec. 2021

Summary: BananaHome is a modern Australian e-commerce website that focuses on stylish and customizable furniture for contemporary living spaces.

Key Responsibilities:

• Designed dynamic filtering and product pages with React and Tailwind CSS;
• Built SSR-based frontend and backend APIs in Nest.js;
• Integrated Sanity CMS and Stripe for payments and content management.

Technologies: React, Tailwind CSS, Node.js, Nest.js, Sanity CMS, Stripe API, REST, GraphQL, TypeScript, SSR, SWR, AWS, PostgreSQL.

Junior Full-Stack Mobile Engineer, My Books - EdTech Mobile App

Duration: Mar. 2020 - May 2021

Summary: My Books - Unlimited Library is a mobile application that provides users with access to a vast digital library of audiobooks and eBooks across various genres, available for online and offline listening or reading.

Key Responsibilities:

• Built mobile frontend with React Native, focusing on usability and content consumption;
• Integrated backend APIs for audiobook streaming and user syncing;
• Developed offline caching with SQLite and secure media delivery via AWS S3.

Technologies: React Native, Redux, TypeScript, Node.js, Express.js, REST APIs, GraphQL, Firebase, SQLite, AWS S3.

Education

• National University Polytechnic, Master’s Degree in Computer Science (Sep 2020 - May 2022);
• National University Polytechnic, Bachelor of Computer Science (Sep 2016 - Jun 2020).