Mykyta K.

Full-stack engineer with 6+ years of commercial experience building production web applications. My primary stack is JavaScript / TypeScript with React on the frontend and Node.js / Express on the backend, backed by a solid Java / Spring background for everything that needs heavier server-side logic. I work end-to-end on web products: business logic, REST and WebSocket APIs, database design, frontend implementation, third-party integrations, testing, and deployment. I'm equally comfortable joining an existing codebase and shipping features inside it, or starting a new project from a blank repo. What I do best: 🔹 Full-stack web apps — React / Redux / TypeScript on the frontend, Node.js / Express on the backend, PostgreSQL or MongoDB for data. Clean architecture, REST APIs, real-time features over WebSocket when needed. 🔹 Java / Spring backend — REST APIs, business logic, data access, JUnit + Mockito test coverage. I spent 3+ years on enterprise Java work (Guidewire P&C insurance platform: PolicyCenter, BillingCenter), which taught me how to keep large codebases maintainable and how to ship inside Agile/Scrum teams across multiple parallel projects. 🔹 Complex API integrations & automation — third-party APIs, custom n8n nodes and workflows, Retool internal tools, Google Apps Script. On my most recent project I built a full-stack platform with deep integrations into financial APIs (DeFi protocols via ethers.js, the Bybit exchange, MetaMask), which gave me a lot of exposure to async-heavy systems, real-time data, and reliability work — useful skills that transfer to plenty of non-crypto domains too. What I bring to a project: ✅ End-to-end ownership — from requirements to deployment. ✅ Ability to take over a broken or half-migrated codebase and ship it back to a working state. ✅ Clean, tested, documented code. Unit tests and code review are part of "done," not extras. ✅ Strong API and integration skills (REST, WebSocket, third-party SDKs). ✅ Agile/Scrum communication style — clear updates, realistic estimates, no surprises. Tech stack: Languages: JavaScript, TypeScript, Java, Gosu Frontend: React, Redux, HTML, SCSS/CSS, Tailwind, Material UI Backend: Node.js, Express.js, Spring Framework, Spring Boot Databases: PostgreSQL, MySQL, MongoDB, OracleDB Testing: JUnit, Mockito APIs: REST, WebSocket, third-party API integrations Automation: n8n (custom nodes + workflows), Retool, Google Apps Script DevOps/Tools: Docker, Git, Github, Bitbucket, CI/CD, JIRA, Confluence, Splunk, Postman Also: Web3 / DeFi (ethers.js, AAVE, Uniswap, MetaMask) — available on request Typical projects I'm a strong fit for: — Build a full-stack React + Node.js / TypeScript product from scratch — Add features, fix bugs, or refactor an existing React or Node.js codebase — Design and implement a REST or WebSocket API on Node.js or Spring Boot — Java / Spring Boot backend development and microservices — Frontend work in React (forms, dashboards, admin panels, internal tools) — Third-party API integrations and workflow automation (incl. n8n) — Take over a stalled or messy project and bring it to a working, maintainable state I'm available for both short fixed-price tasks and long-term hourly engagements. If you have a clear spec, a half-finished project, or just an idea you want to scope out — send me a message with a few details and I'll come back with concrete next steps. Keywords: JavaScript, TypeScript, React, React.js, Redux, Redux Toolkit, React Hooks, Next.js, Node.js, Express.js, Express, JavaScript Developer, TypeScript Developer, React Developer, Node.js Developer, Full-Stack Development, Full-Stack Developer, Frontend Development, Frontend Developer, Backend Development, Backend Developer, Web Development, Web Application Development, SPA, Single Page Application, Responsive Web Design, HTML, HTML5, CSS, CSS3, SCSS, Sass, Tailwind CSS, Bootstrap, Material UI, UI Development, UI Components, Dashboard Development, Admin Panel, Internal Tools, Form Development, Java, Java Developer, Spring, Spring Framework, Spring Boot, Spring MVC, Spring Data, Hibernate, JPA, Maven, Gradle, REST API, RESTful API, REST API Development, API Integration, API Design, Third-Party API Integration, Web Services, JSON, WebSocket, WebSockets, Real-Time Applications, Microservices, Backend Architecture, Server-Side Development, PostgreSQL, MySQL, MongoDB, NoSQL, OracleDB, SQL, Database Design, Database Modeling, ORM, JUnit, Mockito, Jest, Unit Testing, Integration Testing, Test-Driven Development, TDD, Code Review, Refactoring, Legacy Code Migration, Codebase Refactoring, Performance Optimization, Bug Fixing, Debugging, Docker, Git, GitHub, Bitbucket, GitLab, CI/CD, GitHub Actions, JIRA, Confluence, Postman, Splunk, Agile, Scrum, Kanban, MVP Development, SaaS Development, Web App Development, Cross-Browser Compatibility, Workflow Automation, n8n, n8n Custom Nodes, Business Process Automation, Retool, Google Apps Script, Google Sheets Automation, Web3,