Engineering ideas into digital experiences.

Independent full-stack and mobile engineer. From elegant websites to intelligent mobile applications and complex business platforms, I design, build, integrate and deliver software end to end.

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More than code. Complete solutions.

One engineer takes your idea from the first sketch to a product that is live, deployed and handed over.

  1. End to end

    Interface, API, data and release in one pair of hands.

  2. Built as a system

    Data model, failure modes and future changes designed in from day one.

  3. Delivered turnkey

    Scope agreed in business terms, shipped to production, ready to use.

One engineer.The whole product.

Scroll to assemble the layers I work across every week, from the database to the phone in your hand.

  1. BackendNestJS services with typed modules, roles and background jobs
  2. DataPostgreSQL schemas, migrations and Redis caches
  3. API & eventsREST APIs, webhooks and RabbitMQ events that keep systems in sync
  4. WebNext.js interfaces, server-rendered and fast on every device
  5. MobileFlutter and native iOS apps, offline-first when it matters
  6. AILLM and vision features wired in where they earn their place

Assembled, tested and shipped as one product.

Selected work.

Five products I ship end to end: web, mobile apps, the systems behind them, and the sites that sell.

  1. Live

    Fitofan

    Sports platform: web, mobile apps and the backend behind them

    One platform for athletes, coaches, clubs and fans: a web app in 11 languages, iOS and Android apps, and one backend that I own end to end.

    • Live scores, match events and commentary streamed into web and mobile in real time
    • Payments through Finix, with Stripe, PayPal, Square, LiqPay and Mercado Pago verifiers
    • AI assistant with 15 domain tools, voice transcription and generated media
    • iOS Live Activities for live match scores, a native extension around Flutter

    Senior Full-Stack & Mobile Engineer · 2024 – 2026

    • Next.js
    • NestJS
    • Flutter
    • PostgreSQL
    • RabbitMQ
    Read the case

  3. Competition Day

    Check-in, judging, scoring and live broadcast for Fitofan events

    Five apps that run a tournament on site: check-in and judging on a desktop, judge consoles on phones and tablets, a bridge to scoring hardware, phone cameras that broadcast with a live scoreboard, and multi-camera replay.

    • Works without internet: event data cached locally, results queued and synced when the connection returns
    • Devices find each other on the venue network through UDP discovery and TCP sockets

    Lead Engineer: Flutter, native iOS and Android, desktop · 2024 – 2026

    • Flutter
    • Swift
    • Kotlin
    Read the case

  5. Websites and stores

    Storefronts, corporate sites and member portals, delivered turnkey

    Sites and shops built around how each business actually sells, delivered ready to use: design, build, content, integrations, deployment and admin tools the staff run themselves.

    • A Next.js storefront with its own admin, catalog import, delivery lookups and payment-method flows
    • Card payments through Finix and membership fees through PayPal

    Full-Stack Engineer · 2019 – 2026

    • Next.js
    • Supabase
    • Feature-Sliced Design
    Read the case

What I engineer.

Six connected areas of one practice. Each card names what I build there and the shipped systems behind it.

  1. Web & E-commerce

    Websites and stores delivered turnkey, from the first screen to deployment: Next.js storefronts with their own admin, and custom components inside 1C-Bitrix.

    • A Next.js storefront with its own admin, catalog import, delivery lookups and payment-method flows
    • 140+ pages in 11 locales with translation parity checked in CI
    • Bitrix sites with a generated catalog and webhook publishing
    • Next.js
    • TypeScript
    • FSD
    • Supabase
    • 1C-Bitrix
    Seen in
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  2. AI & Motion Intelligence

    AI where it does a job: an assistant that acts through domain tools, voice that becomes text, generated media, and movement recognition that reads exercise states from motion signals.

    • OpenAI tool-calling assistant with 15 domain tools, Whisper transcription and generated media
    • Exercise-state classification from movement signals in Flutter
    • Model integration experiments on IBM watsonx.ai
    • Flutter
    • OpenAI API
    • IBM watsonx.ai
    • Replicate
    Seen in
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  3. Multi-Tenant Platforms

    One codebase serving many organizations: each gets its own domain, content and data, and every request is resolved and authorised on the server before it runs.

    • A guard resolves each club by id or slug and checks membership before any handler runs
    • 80+ admin pages in 11 locales on one shared platform
    • Members, schedules, check-in, billing and analytics, isolated per organization
    • Next.js
    • Cloudflare Workers
    • Supabase
    • PostgreSQL
    Seen in
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  4. Mobile Engineering

    Flutter apps for iOS and Android that carry a real operation: check-in at the door, scoring in the hall, results that keep moving when the venue's internet does not.

    • Event apps that work offline: data cached on the device, results queued and synced when the connection returns
    • Devices find each other on the venue network through UDP discovery and TCP sockets
    • iOS Live Activities for live match scores, a native extension around Flutter
    • Flutter
    • Dart
    • Clean Architecture
    • BLoC
    • Riverpod
    Seen in
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  5. Backend & Business Systems

    One backend behind web and mobile: the services, data and access rules a business runs on every day, structured so they can change without a rewrite.

    • NestJS with 90+ modules, PostgreSQL with 290+ migrations, Swagger and health checks
    • Event-driven sync over RabbitMQ with idempotent consumers and a dead-letter queue
    • Redis caching with decorator-driven invalidation and Socket.IO gateways for live sessions
    • NestJS
    • TypeScript
    • PostgreSQL
    • Redis
    • RabbitMQ
    Seen in
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  6. Integrations & Automation

    Payments, webhooks, notifications and publishing wired into one flow, so money and data move on their own and every event leaves a trace.

    • Eight payment providers plus cash behind one adapter, with encrypted credentials and idempotent webhooks
    • Live fixtures, results and odds from sports-data feeds; publishing to Meta, TikTok, LinkedIn and YouTube
    • Phones streaming to Amazon IVS with a live scoreboard composited into the picture
    • Payments
    • Webhooks
    • Meta API
    • TikTok API
    • Notifications
    Seen in
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How it's built.

Six questions worth asking any engineer before you sign, answered with what is already running in production.

  1. Will it be fast?

    Pages render on the server and ship only what the screen needs; heavy work runs in the background, hot data is cached, and it is measured before it goes live.

    • Redis caching with decorator-driven invalidation in front of PostgreSQL
    • Server-rendered Next.js with static pages per locale: 140+ pages in 11 languages
    • Next.js
    • Server Components
    • Redis
    • Cloudflare

  2. What happens when a payment fails at 2 a.m.?

    Nothing is charged twice and nothing is lost: every call that moves money carries an idempotency key, every event is recorded, and a retry is safe to click.

    • Eight payment providers plus cash behind one adapter, with idempotent webhooks
    • RabbitMQ with idempotent consumers, a dead-letter queue and a correlation id on every message
    • NestJS
    • RabbitMQ
    • Webhooks
    • Payment providers

  3. Can another developer take over?

    Yes, without archaeology: one architecture across projects, typed end to end, type-check and tests as a gate before every deploy, and the message topology written down.

    • A type-check and Jest gate, a Docker image and a scripted deploy, the same on Fitofan and GymTeam
    • One RabbitMQ contract with 29 routing keys, a typed envelope and documented topology, shared by two products
    • TypeScript
    • Feature-Sliced Design
    • Jest
    • Docker
    • GitHub Actions

  4. Is my data safe and separate from everyone else's?

    Access is decided on the server for every request, credentials are encrypted at rest, and each organization sees only its own rows.

    • A guard resolves each club and checks membership before any handler runs
    • AES-256-GCM credential storage; 66 SQL migrations with row-level security on the storefront
    • PostgreSQL
    • Supabase
    • Row-level security
    • AES-256-GCM

  5. Will it work on phones, offline, in my customers' languages?

    One Flutter codebase for iOS and Android, native Swift where the platform demands it, offline-first where the venue's internet fails, and translations with parity checked in CI.

    • Event apps cache data locally and sync results when the connection returns
    • 11 locales and roughly 10,000 translation keys with parity checked in CI; eight languages on this site
    • Flutter
    • Swift
    • SQLite
    • next-intl

  6. Where does AI actually help, and where is it hype?

    AI goes in only where it does a job, tested in a sandbox first: an assistant that acts through domain tools, voice that becomes text, generated media, movement recognition.

    • OpenAI tool-calling assistant with 15 domain tools, Whisper transcription and generated media
    • Exercise-state classification from movement signals in Flutter; model experiments on IBM watsonx.ai
    • OpenAI API
    • Whisper
    • IBM watsonx.ai
    • Replicate

I select tools based on the problem to solve, the product lifecycle, and maintainability.

Frontend

Server-rendered React with typed components, a design system and translations built in from day one.

  • Next.js
  • React
  • TypeScript
  • Feature-Sliced Design
  • Tailwind CSS
Mobile

Cross-platform Flutter where it fits, native Swift where the platform demands it.

  • Flutter
  • Dart
  • Clean Architecture
  • BLoC
  • Riverpod
  • Swift
  • SwiftUI
Backend & Data

NestJS services on PostgreSQL, with Redis for caching and RabbitMQ when systems need to talk asynchronously.

  • NestJS
  • Node.js
  • PostgreSQL
  • Redis
  • RabbitMQ
  • Supabase
  • Firebase
Cloud & Infrastructure

Containers, CI/CD and managed cloud services configured for predictable releases and sane costs.

  • Docker
  • GitHub Actions
  • Google Cloud
  • IBM Cloud
  • Cloudflare
  • Vercel
  • Nginx
AI & Integrations

LLM, vision and payment integrations added where they change the product, with sandbox-first testing.

  • OpenAI API
  • IBM watsonx.ai
  • Replicate
  • Payment providers
  • Webhooks
  • Meta & TikTok APIs

What can I build for you?

Clear business solutions, from a focused website to a connected software platform.

  1. Websites & E-commerce

    Landing pages, business sites, catalogs, custom stores and content systems.

    A landing page for a campaign, a corporate site your team can edit, or a store that sells while you sleep.

    WHAT YOU GET

    • Every page designed and built on one design system, not a template
    • Content you can edit, with SEO and analytics wired in
    • Deployed on your domain with a working contact or checkout flow

    From$1,800

    Seen in
    Discuss this service

  2. Mobile Applications

    Cross-platform Flutter apps with connected backend workflows.

    A customer app for iOS and Android built once in Flutter, with the backend it needs behind it.

    WHAT YOU GET

    • One Flutter codebase, published to the App Store and Google Play
    • The backend and admin the app needs behind it
    • Offline behaviour, notifications and payments where the product needs them

    Custom quote

    Seen in
    Discuss this service

  3. Custom Business Software

    Administrative systems, operational tools, APIs, and custom platforms.

    An internal platform that replaces spreadsheets: roles, workflows, reports and the integrations around them.

    WHAT YOU GET

    • Roles, workflows and reports that replace the spreadsheets
    • APIs and integrations with the tools you already run
    • Documentation, a deploy pipeline and a clean handover

    Custom quote

    Seen in
    Discuss this service

  4. AI & Third-Party Integrations

    Intelligent features, payment integrations, notifications, and automation.

    Assistants, document and image features, payments, notifications and the glue between the tools you already use.

    WHAT YOU GET

    • Assistants, document and image features that do a job, tested in a sandbox first
    • Payments, webhooks and notifications wired end to end
    • Automation of the steps a person copies by hand today

    Custom quote

    Seen in
    Discuss this service

Built around your requirements.

Clear scope, transparent estimates, and a technical approach suited to your needs.

  1. Landing pages

    From$1,800

    • One page, designed and built
    • Responsive, fast, SEO basics
    • Contact form and analytics
    • Deployed on your domain
    Discuss your project

  2. Business websites

    From$2,900

    • Up to eight pages on one design system
    • Content you can edit without a developer
    • Ready for several languages
    • SEO, analytics and deployment
    Discuss your project

  3. E-commerce

    From$4,700

    • Catalog, cart and checkout
    • Online payments or order requests, your call
    • Admin panel and product import
    • SEO and performance tuned
    Discuss your project

  4. Mobile applications

    Custom quote

    • Scope and estimate after a short discovery call
    • Flutter app for iOS and Android
    • Backend, releases and store publishing
    Discuss your project

  5. Business platforms & AI

    Custom quote

    • Scope and estimate after a short discovery call
    • Multi-tenant platforms, dashboards and integrations
    • AI features where they earn their place
    Discuss your project

WHAT MOVES THE PRICE

  • How many screens, pages and languages
  • Payments, integrations and the systems we connect
  • Design from scratch or from your existing brand

Every price includes typed code, tests, deployment and a clean handover.

Prices in US dollars.

From concept to delivery.

Four stages, and something you can hold at the end of each one.

  1. Understand

    A short discovery call, then a written scope and estimate: what we build, what we leave out, and what it costs.

  2. Architect

    The shape of the solution before code: data, services, integrations and the first screens to react to.

  3. Build

    Weekly iterations on a staging address you can open and click; type-check and tests gate every build.

  4. Deliver

    Release, documentation, the deploy pipeline and the repository handed over, so the product runs without me.

Valerii Vvedenskyi

Valerii Vvedenskyi

Senior Full-Stack & Mobile Engineer · Toronto, Canada

LinkedIn

An engineer behind the entire experience.

I design, build and run software end to end: web interfaces, mobile apps, the services behind them and the infrastructure they live on. Six years in commercial teams taught me to care about the whole product, not a single layer.

Engineering opportunities & collaborationDownload résumé

Experience

  1. 2024 – 2026 · Toronto

    Senior Full-Stack & Mobile Engineer · Fitofan

    Owned web, mobile and backend delivery for an athlete platform: Next.js, NestJS, Flutter, RabbitMQ, AI integrations and cloud operations.

  2. 2020 – 2023 · Dnipro / London

    iOS Engineer · Y-Tree

    Native iOS for a wealth-management service: Open Banking and KYC integrations, SwiftUI and TCA migration.

  3. 2019 – 2020 · Dnipro

    Junior Backend Engineer · Sunrose

    Backend features and layered-architecture improvements for an e-commerce web application.

Have something in mind?

Tell me what you want to build. We can define the scope and the best technical approach.

Or write directlyvalerii.vvedenskyi@gmail.com