Senior engineering, delivered by subscription.

One developer. Full ownership. Human expertise, AI speed.

From AI agents to SaaS platforms — I build and maintain your product, so you can focus on growing your business.

No credit card required

0h

Onboarding

0+

Projects shipped

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Faster than traditional dev

Denys Zaichenko

Why Me

AI can prototype. But who ships it to production?

Tools like Lovable or Claude Code are great at generating code and drafts. That's where their job ends — and where mine begins.

I'm a senior full-stack developer with 8+ years of experience. I use AI the way a craftsman uses precision tools: to move faster without cutting corners. You get production-grade work, clean architecture, and a developer who's still there six months later.

8+ yrs

Senior engineering

5.0 ★

Upwork rating

CET

EU timezone

Certified

Claude Code user

Testimonials

What clients say

Real feedback from Upwork. 5.0 average across every engagement.

“Excellent developer! High-quality delivery and great communication on two of my personal projects. He is efficient, professional, and easy to work with. Highly recommended!”
High-Quality DeliveryGreat CommunicationEfficient

Full-Stack Dev (Python/Next.js): End-to-End SaaS Platform

Mar 2026 · via Upwork

“Denys is a great specialist, and he always does more than required! Very highly recommended!”
Committed to QualitySolution OrientedClear Communicator

Technical Strategy & Architecture Roadmap for AI-powered MVP

Jan 2026 · via Upwork

Rated 5 stars — no written review

Solution OrientedClear CommunicatorAccountable for Outcomes

Full-Stack Dev (Python/Next.js): Pricing Intelligence Platform

Mar 2026 · via Upwork

See full profile on Upwork

How I'm Different

Senior developer. AI-native workflow. One subscription.

Prototyping

Feasibility review first

vs AI·Fast drafts

Building

Clean, production-ready code

vs AI·Code scaffolding

Deploying

I handle deployment

vs AI·Manual handoff

Maintaining

Ongoing, included

vs AI·Not supported

Scaling

I own the codebase

vs AI·Not supported

“AI is your co-pilot. I'm your engineer.”

I don't fight automation — I'm built on it. You bring the idea, AI drafts the first pass, I ship the production system your business relies on.

vs Per-Project

Why subscription beats per-project work

Reliability

One developer, full accountability, always reachable

vs Per-project·Depends on the person. Disappears mid-project.

Availability

Async-first, CET timezone, response within 4h

vs Per-project·Limited hours, timezone issues

Project Management

I manage end-to-end

vs Per-project·You handle scope, QA, delivery

Pricing

Flat monthly. Cancel anytime.

vs Per-project·Hourly. Balloons with revisions.

Delivery speed

2–3 days per task, sprint-based

vs Per-project·Often delayed to bill more hours

Quality

Senior engineer, 8+ years, 50+ shipped products

vs Per-project·Varies. No long-term accountability.

Codebase context

Knows your codebase deeply

vs Per-project·Starts from zero every gig

Support

Ongoing. I maintain what I build.

vs Per-project·Ends when the gig closes

Freelancers build gigs. I build products that scale.

What I Build

Everything your product backlog needs

Recent Work

Shipped projects

18+ production systems delivered — AI agents, RAG, SaaS platforms, and scraping pipelines.

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

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
Live

Enterprise RAG Document Intelligence

Enterprise RAG platform turning thousands of documents into a searchable knowledge base. Hybrid search, page-level citations, accuracy monitoring.

LlamaIndex · Pinecone · Python · OpenAI APIView Project
Live

AI Voice Agent for Phone Calls

AI voice agent answering calls, qualifying leads, booking appointments 24/7. Real-time transcription, sentiment analysis, 20+ languages.

Vapi · Retell AI · Python · LiveKitView Project

Real-Time SaaS Platform & Admin Suite

Real-time SaaS for a digital marketplace. Custom SQL RPC, Role-Based Access Control, real-time updates, admin panel with analytics.

React · Supabase · TanStack Query · Recharts

Pricing

Subscribe to a senior engineer

Transparent turnaround, priority queue on higher tiers, full ownership of what gets built.

Most Popular

Builder

$2,999/month

For teams shipping weekly

  • 2 concurrent active requests
  • Any scope — features, refactors, integrations
  • 2–3 business days per standard task
  • 4h priority response on weekdays
  • Slack / Telegram + weekly 30-min sync call
  • Full code ownership
Start Builder Plan
What counts as a request? Any scoped unit of work — from a bug fix to a new feature. Small fixes under 1 hour don't occupy your slot. Larger projects (>2 weeks) get broken into requests during kickoff.

Pause or cancel anytime — no commitments

Risk-free: Not satisfied in the first week? Full refund, no questions asked.

How It Works

How work flows

  1. 01

    Submit a task

    Drop your request via Slack or a shared board: new feature, bug, integration, anything.

  2. 02

    Scope & align

    I clarify requirements, break it into a clear deliverable, and confirm the timeline before touching code.

  3. 03

    Build

    I build with AI-assisted speed and human-grade review. You see progress, not silence.

  4. 04

    Ship & support

    Deployed, documented, and ready. I stay on for follow-up iterations — it's included.

FAQ

Frequently asked questions