Full-Stack Developer

Denys Zaichenko

AI chatbots, data extraction, web scraping, full-stack apps — modern stack, fast delivery.

50+ projects · 5.0★ Top Rated on Upwork · Escrow-protected · Porto, Portugal

“Denys thinks like a product owner, not just a freelancer, which made the whole process smooth.”

— Upwork Client
Denys Zaichenko

About

About Me

Full-stack developer based in Porto, Portugal. I build AI-powered tools, landing pages, dashboards, and automation systems for agencies and startups. Modern stack, clean code, fast delivery.

Next.jsReactTypeScriptPythonClaude APIOpenAISupabaseTailwind CSSFastAPILangChainPlaywright
50+ projects delivered5.0 on UpworkCET timezoneSame-day response
Upwork5.0 ★ · View Profile

What I Build

Services

AI Chatbots & Agents

WhatsApp, Telegram, voice agents, multi-agent systems. Lead qualification, support, booking 24/7.

OpenAIClaudeLangChainPython

AI Data Extraction

Extract structured data from PDFs, contracts, invoices with LLM pipelines. 99%+ accuracy.

OpenAIFastAPIPythonRAG

Web Scraping & Data Pipelines

Lead generation at scale. Anti-detection, proxy rotation, real-time monitoring. REST API included.

PythonPlaywrightPuppeteerProxy

Full-Stack Web Apps

SaaS platforms, admin panels, real-time dashboards. Supabase, auth, payments — production-ready.

ReactTypeScriptSupabaseNode.js

Landing Pages

Next.js + Tailwind. Mobile-first, 95+ PageSpeed, i18n-ready. Delivered in 3–5 days.

Next.jsReactTailwind CSSTypeScript

Selected Work

Recent Projects

Live

B2B SaaS — AI Web Scraping & GPT Data Extraction

AI-powered web scraping platform with GPT data extraction from PDFs. Automated data pipelines for B2B clients at scale.

Python · OpenAI GPT-4 · Web Scraping · Next.jsView Project
Live

E-commerce Price Scraping & Monitoring

Price monitoring platform scraping competitor prices across Amazon, Shopify, WooCommerce. Tracks 12,000+ products with AI pricing suggestions.

Python · Playwright · Scrapy · Next.jsView Project
Live

WhatsApp & Telegram AI Chatbot

Multi-channel AI chatbot for WhatsApp and Telegram. Visual flow builder, AI lead scoring, 95+ languages, CRM integration.

Python · OpenAI GPT-4 · WhatsApp API · Next.jsView Project
Live

Multi-Agent AI Orchestration

Mission-control for multi-agent AI systems. Live topology map, workflow builder, real-time monitoring, message tracing across agent swarms.

LangGraph · CrewAI · Python · FastAPIView Project

Client Feedback

What Clients Say

“He delivered a powerful platform with complex analytics that actually looks great. Denys thinks like a product owner, not just a freelancer, which made the whole process smooth. If you need a dev who cares about the final quality, he is the one.”

Upwork Client — B2B SaaS Project

“Denys is a great specialist, and he always does more than required! Very highly recommended!”

Upwork Client — Technical Strategy & Architecture Roadmap

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Hire Me on Upwork

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Let's Build Together