Hi, I'm Denis 👋
Fullstack developer with 5 years of experience. Building backend services, cloud infrastructure, AI pipelines, and web and mobile apps. Passionate about scalable architecture and mentorship.
DR

About

Full Stack Developer with 5 years of experience building web applications end-to-end, with a strong focus on backend development and infrastructure. Works primarily with TypeScript and JavaScript.

Backend. APIs and services with Node.js and NestJS — database schemas, migrations, and data processing; async job processing with BullMQ and Redis; API caching and request throttling; Google and Apple authentication; payment integration with Stripe. Databases: PostgreSQL, MongoDB, Neon, and Firebase, with Pinecone for vector search, using Prisma ORM, TypeORM, and Drizzle Kit.

Infrastructure & deployment. Containerized deployment with Docker and CI/CD pipelines; AWS — S3, ECS, RDS, IAM, and CloudWatch Logs; a full observability stack with Prometheus, Loki, Node Exporter, and Grafana; load testing with k6.

AI integrations. OpenAI GPT, Anthropic, and Gemini for file generation (pdf, docx), chat systems with custom instructions, image analysis, and internet search. Built image generation pipelines that train custom models from user photos and generate new images from them.

Frontend. Performant, cross-browser interfaces with React, Next.js, and Tailwind CSS; mobile apps with React Native and Expo, published to the App Store and Google Play; real-time features with WebSocket, WebRTC, and Web Audio; authentication flows with Google, Apple, Facebook, email, and phone.

Engineering approach. Building scalable, maintainable systems — reducing duplication and applying KISS, DRY, and SOLID. Mentors junior developers and contributes to architectural decisions.

Work Experience

S

Stealth Startup

August 2025 - Present
Full Stack Developer
- Developed new features and optimized backend processes across projects built with NestJS in a monorepo setup. - Migrated and refactored business logic between services, improving storage structure and code reuse across the codebase. - Designed and maintained PostgreSQL schemas and migrations, and optimized slow queries — cutting response times from ~8s to ~300ms. - Conducted load testing with k6 across multiple server scenarios to find the most efficient configuration, doubling throughput. - Implemented API caching, request throttling, and full async job processing with BullMQ and Redis for background and scheduled tasks. - Set up a complete observability stack — Prometheus, Loki, Node Exporter, and Grafana — with dashboards, running in Docker. - Implemented Redis-backed WebSocket communication across all required endpoints and wrote the socket documentation for the team. - Integrated Stripe payments and Google and Apple sign-in, including session management and access control. - Implemented AI-powered community validation with the OpenAI API to automatically review user-submitted content. - Deployed and operated services on AWS: S3, ECS, RDS, IAM, and CloudWatch Logs. - Set up and maintained CI/CD pipelines and Docker-based deployment, conducted code reviews, and mentored developers. - Developed two multilingual, SEO-optimized landing pages with Next.js. Key projects: - Judah — a gamified Bible study app with quizzes, reading streaks, leaderboards, and a community feed. - TwoBetter — a relationship guide with gamified lessons and quizzes on emotional maturity, healing, and intentional dating.
I

Incant

April 2024 - August 2025
Full Stack Developer
- Built AI-powered automation pipelines (RAG, MCP) for document analysis, schema extraction, multi-step workflows, image generation, chunking, and deduplication using OpenAI, Anthropic, Gemini, and Mistral. - Trained custom image models from user photos and built the generation pipelines on top of them. - Implemented AI features: file generation (pdf, docx), chat systems, image analysis, and web search. - Built backend APIs with Node.js, NestJS, and Hono — data processing, migrations, batch jobs, retries, and data consistency. - Developed and maintained React Native iOS and Android apps, published end-to-end to the App Store and Google Play. - Built UI components, cards, forms, editors, and interactive workflows with Next.js and Tailwind CSS, improving UX, performance, and page logic. - Designed and operated the data layer across Supabase, PostgreSQL/Neon, MongoDB, Redis, and Firebase with Prisma ORM and Drizzle Kit, deployed on Google Cloud. - Integrated authentication systems — Kinde, Better Auth, and social logins — with session management, password recovery, and access control. - Managed infrastructure and developer tooling: Turborepo + pnpm, Docker, ESLint/Prettier, CI/CD pipelines, and Jest; conducted code reviews and mentored developers. Key projects: - Gymate — fitness platform built solo end-to-end: trainer web app for workout programs, meal plans, and client progress reports, plus a client mobile app with workout logging, calorie tracking, and AI food recognition from photos. - BeachMe — beach reservation app with payments (frontend + backend): owners lay out tables, chairs, and sunbeds; clients find beaches via Google Maps and book and pay for specific spots. - Kuku — voice-driven notes and reminders app with AI transcription and processing; built frontend and backend. - Incant — dynamic workflow builder with node creation, connections, template loading, and element search.
<

<DIA/>

August 2022 - April 2024
Frontend Developer
- Developed and optimized the frontend architecture in React for two OLX-style marketplace platforms, one of them built for the Asian market — component structure, routing, and state management with Redux Toolkit. - Built real-time communication end-to-end: chat, video and audio calls, voice messages, and notifications with WebSocket, WebRTC, and Web Audio. - Implemented user registration and authentication with Firebase Auth, including Google login, with session handling and access control. - Strengthened client-side security through token handling and storage, input validation, and file upload restrictions. - Integrated the Google Maps API for location-based search and listing features across the marketplace. - Implemented file upload and download over REST APIs with upload progress tracking and client-side file previews. - Improved runtime performance through lazy loading, memoization of heavy components, and reduction of the existing codebase. - Wrote reusable TypeScript/JavaScript modules covered by Jest unit tests. Key projects: - Moow — classifieds marketplace where users post listings and sell goods directly to buyers, in the style of OLX. - Moow Landing — marketing site presenting the Moow marketplace and driving user sign-ups. - Tentai — the same marketplace product, built for the Asian market.
B

BulBank

February 2022 - July 2022
Full Stack Developer
- Built a Telegram clone end-to-end, covering both the React interface and the REST API behind it. - Developed the REST API foundation and refactored existing request handlers. - Created and optimized shared UI components reused across internal projects. - Built responsive interfaces with HTML, CSS/SCSS, JavaScript and TypeScript.

Skills

languages

TypeScript
JavaScript

frontend

React
Next.js
Tailwind CSS
Radix UI
Shadcn UI
Redux Toolkit
Zustand
Jotai
TanStack Query
Web RTC
Web Audio
Web Socket

mobile

React Native
Expo
App Store / Google Play publishing

backend

Node.js
NestJS
Hono
Fastify
REST API
Socket.io
BullMQ
Cron Jobs
Zod
class-validator
Joi
Sharp
Stripe

databases

PostgreSQL
MongoDB
Neon
Supabase
Firebase
Redis
Pinecone
Prisma ORM
Type ORM
Drizzle ORM

authentication

Google Auth
Apple Auth
Facebook Auth
Firebase Auth
Email & phone authentication

infrastructure

Docker
AWS (S3, ECS, RDS, IAM, CloudWatch Logs)
Google Cloud
CI/CD (GitHub Actions)
Turborepo
pnpm
npm
bun
Git / GitHub

monitoring

Prometheus
Grafana
Loki
Node Exporter
k6 (load testing)

ai

OpenAI API
Anthropic Claude API
Gemini API
FalAi
AI / LLM pipelines
RAG
Image generation & analysis
PDF / DOCX generation

testing & quality

Jest
ESLint
Prettier
My Projects

Check out my latest work

I build full-stack products end-to-end — from scalable backends and AI integrations to polished mobile and web apps. Here's everything I've worked on.

TwoBetter

TwoBetter

TwoBetter Learning is a relationship guide that helps people build healthy connections, using gamified lessons and quizzes to explore emotional maturity, healing, and intentional dating, making growing in wisdom and love a little more fun and a little less overwhelming. It shares the same NestJS/PostgreSQL backend foundation as Judah, and I maintain and extend it here as well — async job processing with BullMQ and Redis, observability with Prometheus, Loki, and Grafana, OpenAI-based content validation, and SEO-optimized Next.js landing pages.

Next.js
NestJS
TypeScript
PostgreSQL
TypeORM
Redis
BullMQ
Docker
AWS
Terraform
Prometheus
Loki
Grafana
OpenAI API
Judah

Judah

Judah turns Bible study into an adventure, with quizzes, reading streaks, a leaderboard, and a community of believers, making growing in faith a little more fun and a little less overwhelming. I work on the backend with NestJS, optimizing PostgreSQL queries and cutting response times from ~8s down to ~300ms, running k6 load tests that doubled throughput, and adding async job processing and caching with BullMQ and Redis. I set up observability with Prometheus, Loki, and Grafana in Docker, integrated OpenAI-based community content validation, and built SEO-optimized landing pages with Next.js.

Next.js
NestJS
TypeScript
PostgreSQL
TypeORM
Redis
BullMQ
Docker
AWS
Terraform
Prometheus
Loki
Grafana
OpenAI API
BeachMe

BeachMe

BeachMe is a modern web application for booking seaside accommodations, where users can manage their profiles, authenticate via email/password or social logins (Google, Facebook), view payment history, and configure account security. I worked on the profile pages, implementing advanced user settings, password management, payment history, security options, account deletion, and integrating authentication and session management via Better Auth.

Next.js
React
TypeScript
TailwindCSS
Radix UI
Shadcn UI
Drizzle ORM
Neon.db
Better Auth
Formik
Zod
AWS S3
Firebase
i18n
Enforcy

Enforcy

Enforcy is a web app for AI-powered contract analysis, supporting PDF, DOCX, and TXT files with document viewing, text highlighting, and analytics dashboards. I optimized document upload and analysis logic, including chunking and batch processing, implemented search across document elements and policy mappings, built and improved UI components (document viewer, text highlighting, editor), integrated authentication via Kinde, managed file storage with Supabase, and set up error handling, retries, and data deduplication for the contract analysis pipeline.

React
TypeScript
Vite
TailwindCSS
Radix UI
PlateJS
Chart.js
Supabase
OpenAI API
Kinde
PostgreSQL
Firebase
Drizzle ORM
Zod
PDFLib
Puppeteer

FluxBoard

FluxBoard is a monorepo for a web dashboard and API built around a visual flow editor using React Flow, enabling users to create, edit, and save elements and connections, work with templates, and search for elements. I optimized the React Flow page logic — moving elements, creating new ones, deleting connections, and linking nodes — implemented opening and loading of existing templates with their elements and connections, and added search functionality for elements.

React
React Flow
TypeScript
Redux Toolkit
Vite
NestJS
Drizzle ORM
Prisma ORM
TypeORM
PostgreSQL
Docker
Swagger
OpenAI API
Formik
Yup
Zod
TailwindCSS
Incant

Incant

Incant Workflow Platform is a visual platform for building business workflows and websites with an integrated AI assistant, letting users design custom processes, integrate AI-powered chats, handle file uploads, and automate tasks. I integrated AI (OpenAI/Anthropic) into chats and workflows, built multi-chat with file upload and preview via AWS S3, improved the UI/UX for landing pages, forms, and the admin panel, implemented localization (i18n, RTL), and refactored APIs and integrations.

Next.js
React
TypeScript
TailwindCSS
Shadcn UI
Drizzle ORM
Prisma ORM
PostgreSQL
Supabase
AWS S3
Upstash Redis
OpenAI API
Anthropic Claude
Google Gemini
FalAi
Better Auth
Kinde
React Flow
Puppeteer
PDFLib
MCP
i18n
Kuku

Kuku

Kuku is a mobile reminders and notes app with AI-processed voice notes. On the mobile side (React Native, Expo Router) I implemented phone authentication with code verification, CRUD reminders with daily/weekly/monthly navigation, push notifications with deep links to reminder cards, audio reminders and file uploads, local caching, and UI/UX improvements with custom components and animations. On the backend (NestJS + PostgreSQL) I implemented JWT authentication, CRUD reminders, AI parsing of Hebrew text via OpenAI GPT-4o, audio-to-text transcription via OpenAI Whisper and Google Speech-to-Text, scheduled push notifications, S3 image storage, and Swagger-documented, strictly validated endpoints. I independently built and published the app on the App Store and Google Play.

React Native
Expo
Expo Router
Redux Toolkit
RTK Query
AsyncStorage
NestJS
TypeScript
PostgreSQL
TypeORM
JWT
OpenAI API
Whisper
Google Speech-to-Text
AWS S3
Firebase

Workflow

A platform for building and executing AI workflows using nodes and actions, supporting input/output handling, website and file analysis, OCR scans, structured text extraction (Schema Finder), multi-step execution, and multi-flow support. I built functionality for reading and processing scanned documents and various file formats and integrating them with existing actions, implemented image-model creation and image generation from those models, optimized the workflow execution core and runtime for readability and structure, and helped maintain platform stability and performance.

Bun
TypeScript
Hono
Effect
Docker
MongoDB
Supabase
Upstash Redis
OpenAI API
Anthropic Claude
Google Gemini
FalAi
Puppeteer
PDFLib
Drizzle ORM
Prisma ORM
Zod
Kinde
AWS S3
PostgreSQL
MCP
Globasity

Globasity

Globasity helps startups find ideal corporate partners using AI-driven matchmaking between startups and retailers. I built the frontend end-to-end, implementing the Startups, Retailers, Contacts, and Settings pages, and designed the UI/UX for all roles. I integrated Meilisearch for search and AI-driven matching, set up analytics with Mixpanel, built file uploads for logos and presentations with the UI and server API, and integrated Kinde to fetch and display user data in cards.

Next.js
TypeScript
TailwindCSS
Shadcn UI
Framer Motion
Radix UI
Formik
Yup
Zod
Meilisearch
Mixpanel
Kinde
AWS S3
PostgreSQL
Drizzle ORM
Supabase
Firebase
OpenAI API
Gymate

Gymate

Gymate is a fitness platform I built solo, end-to-end: a mobile app for clients and a web platform for personal trainers. The mobile app (React Native, Expo Router) covers workouts, check-ins/check-ups, a vault, calorie tracking, and AI-based calorie analysis from food photos, with native camera, gallery, PDF viewer, and notification integrations. The trainer web platform (Next.js + TypeScript) includes an admin panel, client management, a workout builder, a nutrition system with a kcal/macro calculator and AI analysis, check-ins and reports, and AWS S3 file storage, with Firebase Auth + JWT authentication and multilingual support. I published the mobile app to the App Store and Google Play myself.

React Native
Expo
Expo Router
Next.js
TypeScript
React 18
Redux Toolkit
React Query
NativeWind
TailwindCSS
Radix UI
Framer Motion
Formik
React Hook Form
Yup
Zod
PostgreSQL
Neon.db
Drizzle ORM
Supabase
Firebase Auth
Kinde
JWT
AWS S3
OpenAI API
Twilio
Puppeteer
PDFLib
Vercel API

Codenames

A web version of the party game Codenames. Two teams each have a leader who gives a one-word clue pointing to one or more words on a shared board, trying to get their team to guess the matching words without picking the words that belong to the other team. A wrong guess ends the turn, and can cost the team a point or hand one to the opponent.

Next.js
TypeScript
Redux Toolkit
TailwindCSS
Shadcn UI
Formik
Zod
NestJS
Drizzle ORM
TypeORM
PostgreSQL
Firebase
Better Auth
JWT
Tentai

Tentai

Tentai is the same OLX-style classifieds marketplace product as Moow, built and adapted for the Asian market. I worked on the frontend architecture, components, routing, and state management, and reused the core real-time communication features (chat, video/audio calls, notifications) and Google Maps integration from the Moow platform.

React
TypeScript
Redux Toolkit
Formik
Zod
WebSocket
WebRTC
WebAudio
MongoDB
JWT
Webpack
i18n
Moow

Moow

Moow is an OLX-style marketplace where users post listings and sell goods directly to buyers. I developed key pages including authorization, filtering, chats, maps, order placement, and order tracking, along with reusable header, footer, and modal components. I also built real-time communication features — chat, video/audio calls, and audio messages with notifications using WebSocket, WebRTC, and Web Audio — and integrated the Google Maps API for location-based search and listings.

React
TypeScript
Redux Toolkit
Formik
Zod
WebSocket
WebRTC
WebAudio
MongoDB
JWT
Webpack
i18n

Moow (landing)

Moow Landing is the promotional landing page for Moow, an OLX-style marketplace for buying and selling goods. I worked on the frontend architecture, built reusable React components, implemented multi-language support (i18n), and translated Figma designs into responsive, pixel-accurate pages.

React
TypeScript
Redux Toolkit
Webpack
HTML5
CSS
i18n
Dove

Dove

Dove is a messaging app similar to Telegram, featuring real-time chats with media and emoji support, file sharing, notifications, and authentication. I developed the frontend (React, Redux Toolkit, Apollo Client), integrated the GraphQL API, implemented JWT-based authentication, and worked on the backend (Node.js, Express, Apollo Server, TypeORM, MySQL). I also added file uploads to AWS S3 and integrated email notifications via Nodemailer and Courier.

React
TypeScript
Redux Toolkit
Apollo Client
Styled-components
React Router
Node.js
Express
Apollo Server
GraphQL
TypeORM
MySQL
AWS S3
Multer
Sharp
Nodemailer
Courier
JWT
bcrypt
Contact

Get in Touch

Want to chat? Just shoot me a dm with a direct question on linkedIn and I'll respond whenever I can. I will ignore all soliciting.