You will get Senior Full Stack Developer | React Node.js | Next.js | Frontend Developer
Project details
š PLEASE NOTE: Before purchasing, please message me directly.
I am Oleksii, a Senior Full Stack Developer with 15+ years and 12,000+ hours of production experience. I specialize in three areas: AI-augmented engineering, React and Next.js headless e-commerce frontend, and React and Node.js full-stack development.
Deliverables: Scalable React and Next.js application, Node.js backend, clean API architecture, and full documentation.
Results: 70+ projects completed across SaaS, Fintech, and E-commerce. Delivery time reduced by 35% through AI-augmented engineering. Bug rate cut by 40%. 25,000+ active users across platforms I have built as a full stack developer and Next.js developer.
š Let's build something great ā message me!
I am Oleksii, a Senior Full Stack Developer with 15+ years and 12,000+ hours of production experience. I specialize in three areas: AI-augmented engineering, React and Next.js headless e-commerce frontend, and React and Node.js full-stack development.
Deliverables: Scalable React and Next.js application, Node.js backend, clean API architecture, and full documentation.
Results: 70+ projects completed across SaaS, Fintech, and E-commerce. Delivery time reduced by 35% through AI-augmented engineering. Bug rate cut by 40%. 25,000+ active users across platforms I have built as a full stack developer and Next.js developer.
š Let's build something great ā message me!
Programming Languages
HTML & CSS, JavaScript, TypeScriptCoding Expertise
Cross Browser & Device Compatibility, PSD to HTML, Performance OptimizationWhat's included
| Service Tiers |
Starter
$59
|
Standard
$999
|
Advanced
$19,999
|
|---|---|---|---|
| Delivery Time | 7 days | 14 days | 30 days |
Number of Revisions | 3 | 5 | Unlimited |
Number of Sections | 1 | 3 | 10 |
Opt-In Form | |||
Autoresponder Integration | |||
Social Media Icon Integration | - | ||
Responsive Design | - | - |
About Oleksii
AI Full Stack Developer React JavaScript Node.js Next.js | NestJS
Kyiv, UkraineĀ - 1:11 am local time
My three main areas of focus are AI-augmented engineering, React and Next.js headless frontend development for e-commerce, and React.js and Node.js full-stack architecture. In simple terms: I help you build fast, modern, and scalable digital products ā and I use AI tools to do it smarter and faster than traditional development.
Over 6+ years I have completed 70+ projects, supporting 25,000+ active users with 99.9% uptime. As a front end developer and full stack developer, my work covers everything from SaaS dashboards and client portals to high-traffic e-commerce storefronts ā all built with clean JavaScript and long-term maintainability in mind.
Here is what I can help you with:
You need a fast, beautiful website or online store. As a Next.js developer and frontend developer, I build high-performance storefronts and landing pages using Next.js, TypeScript, and Tailwind CSS ā integrated with Shopify, Stripe, WordPress, or any headless CMS. My Next.js work consistently delivers top SEO scores and sub-second load times that directly improve your sales and organic traffic. Every project I ship as a front end developer is optimized for speed, accessibility, and conversion from day one.
You need a web app or SaaS platform built from scratch. As a React developer, Node.js developer, and full stack developer, I handle both the frontend and backend ā React.js interfaces, MERN stack architecture, REST and GraphQL APIs, PostgreSQL and Supabase databases ā processing 5M+ API requests per month across 20+ systems delivered for Fintech, B2B SaaS, and marketplace clients. Whether you need a nextjs developer to build a complex multi-tenant platform or a React.js engineer to refactor a legacy frontend, I bring the same level of ownership to every layer of the stack.
You want to build smarter and ship faster using AI. As an AI-augmented engineering consultant, I integrate AI tooling directly into the development process ā reducing bugs by 40% and cutting delivery time by 35% without compromising code quality. This means your product gets to market faster, costs less to maintain, and your engineering team spends less time on repetitive work and more time on what actually matters.
You need a mobile app alongside your web platform. As a React Native developer, I have shipped 10+ cross-platform applications reaching 30,000+ installs on iOS and Android, always collaborating closely with UX UI teams to ensure a polished, consistent experience across every device.
What makes me different from other full stack developers on Upwork is not just the technical range ā it is the business thinking behind every decision. I do not just write code. I ask why we are building this, who is using it, and what outcome the client actually needs. That mindset has helped me deliver 30+ SaaS platforms, achieve 2-3x performance improvements on legacy system migrations, reduce client churn through better UX-driven architecture decisions, and build a track record where the majority of my clients return for their next project.
As a JavaScript developer and React.js engineer who has worked across the full MERN stack for years, I understand that the best frontend developer is one who also understands the backend ā and the best Node.js developer is one who can speak the language of business, not just code. That is the standard I hold myself to on every project, whether I am working as a standalone react developer, a frontend developer embedded in a product team, or a full stack developer owning an entire platform end to end.
My core stack: React, React.js, Next.js, Node.js, TypeScript, Tailwind CSS, MERN stack, PostgreSQL, Supabase, AWS, React Native, Webflow, Shopify, WordPress, NestJS, Firebase, and GraphQL.
Whether you are a founder with a product idea, a startup that needs a reliable nextjs developer and react developer to build fast, or an established business looking for a full stack developer and Node.js developer to scale your platform ā I bring clarity, speed, and senior-level thinking to every engagement.
š Send me a message and let's talk about your project!
Steps for completing your project
After purchasing the project, send requirements so Oleksii can start the project.
Delivery time starts when Oleksii receives requirements from you.
Oleksii works on your project following the steps below.
Revisions may occur after the delivery date.
Message, scope & custom offer
We start by discussing your SaaS / AI product, goal and stack. I then scope the work and send a tailored offer with clear scope, timeline and price ā so you know exactly what you're getting before we start.
Build with weekly demos
I build in focused iterations using Next.js, NestJS, Supabase and AI automation, with working demos each week so you can steer direction early.