10/12/2026 updated
100 % available
Senior Full-Stack Engineer | TypeScript, React, Next.js | SaaS & API Development
Lappeenranta, Finland
Worldwide
Postgraduate Professional Programme - High-Load Systems in Banking, International Banking InstituteAbout me
Senior Full-Stack Engineer with 25+ years of experience, including 12 years as a hands-on CTO. I build SaaS products, APIs and AI-powered applications using TypeScript, Next.js, React, Node.js and PostgreSQL. Experienced in RAG, LLM integrations, automation and production systems.
AI AgentsRAGLLMApplication Programming Interfaces (APIs)Software as a ServicePython (Programming Language)PostgreSQLMySQLNode.jsSoftware ArchitectureRedisNext.jsTypeScriptReact.jsDocker
Senior Full-Stack Engineer and Software Architect with 25+ years of professional experience, including 12 years as a hands-on CTO. I design, build, and maintain production software, from architecture and database design to deployment and ongoing operations.
Core Technologies
Frontend: TypeScript, JavaScript, React, Next.js (App Router), HTML, CSS, Tailwind CSS
Backend: Node.js, REST APIs, PHP, Python, third-party integrations
Databases: PostgreSQL, MySQL, Redis, SQL optimization, caching
Infrastructure: Linux, Docker, CI/CD, Git, deployment and production monitoring
Background processing: BullMQ, queues, scheduled jobs, concurrency, retries, fault tolerance
Payments: Stripe, Mollie, subscriptions, billing, usage limits, VAT handling
AI & Automation
LLM API integration, RAG, hybrid search, vector databases, AI-powered applications
MCP integrations, AI agents, Claude Code, Codex
AI-assisted development, testing, debugging, code review and automation
Architecture & Engineering
SaaS architecture and development from scratch
API design, microservices, external system integrations
Performance optimization, scalability, security and reliability
Legacy system modernization and technical debt reduction
Technical leadership, mentoring, code reviews and product development
Selected Projects
https://pikkuna.fi — Led development of e-commerce automation, integrating payments, logistics and background processing. Reduced order processing time from approximately 30 minutes to under 2 minutes, with 99.4% of orders automated.
https://vatnode.dev — Developed an EU VAT validation API with European Commission VIES integration, caching, fallback mechanisms, subscriptions and usage-based billing.
https://htpbe.tech — Developed a PDF fraud detection API performing 41 automated checks.
https://kri.rocks — Built a SaaS platform for beauty salons, including websites, online booking, scheduling and business management.
I work independently, communicate directly with stakeholders and take responsibility for delivering reliable software. Available for fully remote B2B contracts from Finland. Working languages: English and Russian.
Portfolio: https://iurii.rogulia.fi
Experience
Professional experience10+ years
Freelancer since2001
Languages
FinnishGoodEnglishFluentRussianNative speaker
Project history
Delivering client systems for pi-pi.ee, a B2B e-commerce platform across 32 European markets and 28 languages, plus an internal portal that turns one deal record into 7 trade documents (pro forma, contract, commercial invoice, packing list, CMR). Stack: Next.js, React, TypeScript, Stripe, Notion.
Built and run a production REST API for EU VAT validation with VIES integration, 95% Redis cache hit rate, rate limiting, webhook delivery and Stripe billing, solo from architecture to operations. Stack: TypeScript, Next.js, Hono, PostgreSQL, Redis, Drizzle ORM, Stripe.
Built and run a document-forensics and fraud-detection SaaS with a public REST API featuring 5-layer PDF tampering analysis, tiered billing and algorithm versioning. Stack: Next.js, TypeScript, PostgreSQL, Drizzle ORM, Mollie.