Davyd Kondratenko

• Built a multi-tenant authentication service from scratch with NestJS, TypeORM, and PostgreSQL — implementing a custom OAuth2-inspired login flow with per-tenant user isolation, one-time auth codes exchanged for signed JWTs, redirect URI whitelisting, and automatic code expiration via scheduled cleanup.
• Designed a dual JWT system: asymmetric RS256 tokens verified by client backends locally after fetching the public key once from a standard JWKS endpoint, and symmetric HS256 tokens for MTAS-internal client authentication — with a type field preventing cross-context token misuse.
• Built the Next.js frontend handling user authentication and registration for redirected client app users, with a rewrite proxy to solve browser cookie restrictions. Includes a client dashboard with an embedded integration guide. Used in production for a personal project.

This project was developed to solidify and demonstrate my expertise with newly learned technologies before applying them in a professional environment. It features an integrated Strapi CMS for efficient and code-free content management. The use of Next.js's Static Site Generation (SSG) allows server-side page rendering, minimizing API requests and reducing backend hosting costs. Incremental Static Regeneration (ISR) enables seamless page updates triggered by webhooks from Strapi on content changes. Framer Motion animations and a responsive design further enhance the user experience.

Completed a recruitment assignment under tight time constraints, implementing full functionality for managing nested menu items, including CRUD operations and reordering. The solution was built with Next.js for the frontend, Tailwind CSS for styling, zod for form validation, and dnd-kit for drag-and-drop menu reordering.

Poster is a full-stack web application designed to allow users to add, edit, delete, and rate posts, comments, and replies. The project aimed to apply knowledge of React, Redux, Express, MongoDB, and Playwright in a practical context. Key challenges included selecting appropriate frontend design patterns, designing a MongoDB database, writing comprehensive end-to-end tests to cover all scenarios, and implementing a CI/CD pipeline to automate those tests.