Oleh Khrystenko
Real code. Unfair speed.
Offer Oleh work on your next project.
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Offer work
Uzhgorod,
Ukraine
1 month 6 days back
available for hire
age 40 years
on the service 6 years
Rating
Successful projects
Average rating
Language proficiency level
Українська: fluent
English: intermediate
CV
Full-stack developer with 6+ years of experience. I specialize in SaaS products, AI integrations, and business automation.
Stack: Next.js, NestJS, TypeScript, MongoDB, Stripe, Anthropic API.
What I do:
- SaaS MVP from scratch, production-ready
- AI/LLM integrations (Claude, OpenAI, RAG pipelines)
- Stripe subscriptions, Connect for marketplaces, webhook logi
- Audit and fix of broken projects (including vibe-coded / AI-generated apps)
I deliver working code, not prototypes.
Skills and abilities
Portfolio
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2500 USD SaaS MVP: Auth + Payments + AI
Web Programming
Full-stack SaaS platform built as a production-ready foundation for client MVPs.
What's inside:
– Google OAuth + magic link + password auth
… – Stripe billing: subscriptions, one-time payments, usage-based
– AI chat with streaming and per-message billing
– User dashboard with real-time balance and transaction history
Stack: Next.js, NestJS, TypeScript, MongoDB, Redis, Stripe, Tailwind CSS, Docker.
Timeline: 4 weeks from zero to deployed product.
#Next.js #NestJS #SaaS #Stripe #AI
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5000 USD Wish Hub
Web Programming
Built a complete social wishlist platform from the ground up as a solo developer. The app lets users create profiles, organize gift ideas into collections, share wishlists with friends, and reserve gifts in real time.
What I delivered:
– Full backend architecture: REST API, JWT authentication, role-based access, database design
… – Cloud media storage with AWS S3 for user uploads
– Multilingual support (i18next) with SEO-optimized routing for 2 languages
– Real-time push notifications to alert users about gift reservations and updates
– Privacy controls: users choose who sees their wishlists (public, friends-only, private)
– Auto-extraction of product details from external URLs using Puppeteer
– Advanced filtering, sorting, and search across collections
– Mobile-first responsive UI with Tailwind CSS
– Full deployment and production infrastructure setup
Solo-built from zero to production: 50+ API endpoints, 15+ database collections, cloud file storage, automated data scraping.
#Next.js #NestJS #MongoDB #AWS #TypeScript
