Lead Full-Stack Developer · AI Engineer

Tuomas Hatakka

I build and run agentic AI in production, and in development, demonstrably.

Uusimaa · Finland Shipping for production AI since ,
shipping secure, scalable and accessible code since

Who I Am

Where the judgement comes from

Fifteen years of building software, mentoring the developers around me and sitting in the room with the client — the technical and the commercial halves of the same conversation. With LLMs that mostly turns into judgement: knowing when a model is a genuine multiplier, and when the prompting, evals and glue code will cost more than the feature was ever worth. Underneath sits the detail — each provider's models and their failure modes, harness design, prompt and context engineering, skills, remote and hosted MCP servers, tool calling.

Role
Lead full-stack developer · AI engineer
Based
Vantaa, Finland
Education
BSc, Electrical & Electronics Engineering — Aalto University
Languages
Finnish (native) · English · Swedish · German
Since
AI / LLM
Claude · Gemini · OpenAI · MCP · RAG · LangGraph
Languages
TypeScript · ECMAScript · PHP · Python
Runtimes
Node · Bun · Deno
Front-end
React · React Native · Next.js · responsive CSS / SCSS
Data
PostgreSQL · MySQL · MongoDB · GraphQL · Drizzle
Infra
Vercel · GCP · Azure · AWS · Cloudflare · Docker · GitHub Actions
Design
UI/UX · prototyping · Adobe Creative Suite

AI in Production

Shipped to real users

Agentic AI across the whole chain — in my own pipeline and in clients' production infrastructure. Real LLM features, real users.

Selected Work

Production Implementations

A cross-section — shipped products, open source, and the experiments in between.

Career

Résumé

Experience, selected work, and the stack I build on.

Download résumé (PDF) ↓

Lead full-stack engineer. I build and ship AI products end to end — the LLM pipeline, the app, and the infrastructure underneath. Front-to-back since 2011; the last stretch spent putting agentic AI into production, for my own work and for clients.

Professional experience

  1. Present

    CTO & Principal Engineer GlobalLegalCheck

    CTO and principal engineer leading technical strategy and hands-on development of an AI-native legal-compliance SaaS, running entirely on a self-managed VPS with zero cloud-platform dependency.

    • Own the architecture end to end — a three-repo codebase (Docker, the Next.js 16 / React 19 app, a Payload CMS site), CI/CD and delivery — co-developed with Claude.
    • Built the AI contract interpreter — clause extraction, risk scoring, key-date and missing-clause checks — reducing manual review time by approximately 70% via a private OpenAI-compatible endpoint and a Qdrant embedding and reranking pipeline.
    • Multi-tenant data model with audit logging, OAuth/SSO and SSE-streamed analysis; GDPR- and EU AI Act-aligned by keeping inference and data on EU, self-hosted infrastructure.
  2. Freelance Web Designer & Developer Hummingbird Design (Tmi)

    An independent practice run continuously alongside employment — the studio behind the Hummingbird Design and MONO design systems.

    • Worked in the practice full time between Easywaste and GlobalLegalCheck — a project-partitioned RAG system and Claude Code plugin, self-hosted LLM infrastructure, and the design systems since carried into production work.
    • Delivered numerous client sites and web apps end to end — including custom course-enrolment software and social-media integrations.
    • Built with PHP, jQuery, WordPress, Django and MySQL.
  3. Full-Stack Developer Easywaste Oy & Freelancing

    Rebuilt Easywaste's digital waste-management platform on Next.js, starting as sole developer, with a Gemini-powered AI invoice-analysis engine.

    • Led the full-stack reconstruction of the platform from a legacy v1 onto a modern Next.js 14 / RSC / Supabase / Vercel stack, improving load times and developer velocity.
    • Built a Gemini-powered invoice-analysis engine — multimodal extraction, Finnish Finvoice/Peppol XML parsing and custom OCR, reducing manual data entry by 80% through a 4-phase pipeline with NDJSON streaming.
    • Shipped the business logic — automated tendering with algorithmic commission pricing, subscription billing and CSRD reporting — plus freelance AI features for clients (OpenAI and Claude, function calling).
  4. Software Consultant HiQ Finland

    Full-stack consultant leading front-end architecture on international projects, and a contributor to the Helsinki Design System.

    • Led front-end architecture on European-market projects serving over 100k+ users with React, TypeScript and GraphQL.
    • Contributed development and accessibility (WCAG 2.1) fixes to the Helsinki Design System, named Best Design System at Grand One 2023.
    • Guided teams on scalable front-end patterns and gave internal front-end lectures.
  5. Front-End Developer Nordhealth

    Front-end lead on healthcare triage products, building robust React / TypeScript apps with GraphQL and Django / Node back-ends — in direct contact with the clients using them.

    • Led front-end architecture on healthcare triage products for international clients, reducing triage processing time by 30% across 5+ core medical products.
    • Ran client communication first-hand — gathered requirements, demoed builds and took feedback straight from customers such as the veterinary group Evidensia and the Finnish National Audiovisual Institute (KAVI), with no account manager in between.
    • Built with React, TypeScript and GraphQL over Django/Django REST and Node/Express, on PostgreSQL and MySQL.

Project history

  1. GlobalLegalCheck

    • Architected and built solo an AI-native legal-compliance SaaS — an LLM contract interpreter with clause extraction, risk scoring, key-date detection and missing-clause checks, backed by a private OpenAI-compatible endpoint and a Qdrant embedding and reranking pipeline.
    • Stood up the entire stack on a single self-managed €10/month Hetzner VPS — Docker Compose, Traefik + Let's Encrypt, Postgres 16 / Drizzle, MinIO, self-hosted Documenso e-signing and Umami analytics — with zero AWS / GCP / Azure dependency.
    • Designed a multi-tenant, organisation-scoped data model with audit logging, OAuth/SSO (Google, Microsoft Entra), SSE-streamed analysis, and custom MCP servers for VPS / deploy and CMS tooling — GDPR- and EU AI Act-aligned by keeping inference and data on EU, self-hosted infrastructure.
  2. Easywaste Digital Waste-Management Platform

    • Architected and built from the ground up a comprehensive AI-powered invoice-processing system integrating the Google Gemini API, Finvoice/Peppol XML parsing, and custom OCR for automated waste-fraction categorisation and cost calculation.
    • Developed a complete business platform — an automated tendering engine with algorithmic commission pricing, contract management, equipment tracking, subscription billing, and CSRD compliance reporting — using Next.js 14, TypeScript, Supabase, and Vercel.
    • Implemented a 4-phase extraction pipeline with async batch processing, NDJSON streaming, intelligent fallback detection with Finnish/English keyword mappings, and comprehensive weight/amount estimation algorithms.
  3. Modern AI-Powered Freelance Projects

    • Delivered modern web applications with AI capabilities — OpenAI and Anthropic Claude, streaming multimodal responses and function calling.
    • Architected full-stack solutions using Next.js 15, React 19, Supabase, serverless edge functions, and comprehensive infrastructure including DNS, SSL/TLS, CDN optimisation, and cloud architecture.
  4. Helsinki Design System

    • Contributed to the City of Helsinki's design system — named Best Design System at Grand One 2023 — building accessible (WCAG 2.1) components in TypeScript, React and GraphQL.
  5. Telia B2B E-Commerce

    • Participated in the development of a microservice-based B2B webstore, using TypeScript, React, and GraphQL.
  6. HiQ's Internal E-Commerce Triage

    • Architected and implemented front-end solutions for an e-commerce service using TypeScript, React, and GraphQL.
  7. Wattivahti

    • Developed features for a real-time electricity-consumption monitoring app using React, Redux, and Express.js.
  8. Navisec Health

    • Owned the application architecture — component and state design, API contracts against Django REST, and the real-time layer — and implemented notable features including a Form Builder tool and websocket chat using Django REST, React, and Redux.
    • Back-end development with Django REST, high-quality ORMs, PostgreSQL, and Google Cloud Platform.
  9. Viivi Health

    • Owned the architecture of both the mobile and web applications for a veterinarian video-reception triage service — shared domain model, API design and the booking flow — and implemented them using React Native, React, and Express.js.
    • Included a real-time reservation system with Stripe integration on Google Cloud Platform.
    • Worked directly with the customer throughout — the veterinary clinics adopting the service, Evidensia among them — turning their reception workflows into product requirements.
  10. Provet Cloud

    • Contributed to agile development for multinational clientele as the first front-end developer for the company, implementing features such as a form-builder tool and websocket chat using React, Redux, Django, Django REST, and multi-tenant PostgreSQL.
    • Spoke directly with the clinics running the product — including the veterinary group Evidensia — gathering requirements and demoing releases to their staff myself.
  11. KAVI Elonet

    • Overhauled the Finnish National Audiovisual Institute movie-archive web application (elonet.fi) and designed a new interface for it.
    • Implemented video streaming with captions using PHP and Finna.
    • Worked directly with the customer throughout — agreed scope and interface decisions face to face with KAVI's archive staff, acting as the single point of contact for the institute.
  12. Freelancing Projects

    • Tens of website-development projects and multiple web-application implementations. Clients included Suomen Talousverkko, Tuusulan seurakunta, Nurmijärven seurakunta, UP Suomi Oy, Villa Tammikko, and others.
    • Notable features: custom course-enrolment software with live enrolment and multiple social-media integrations.
  13. Project-Partitioned RAG System & Claude Code Plugin

    • Designed and built an open-source, project-partitioned retrieval-augmented generation system packaged as a Claude Code plugin — FastMCP server, CLI, embedding index with cross-encoder reranking, browser-based viewer, and an automated test suite.
    • Integrated into Claude Code, Claude Desktop, and OpenCode, using Python, FastMCP, the Model Context Protocol, and TypeScript.
  14. Self-Hosted Autonomous AI Infrastructure

    • Provisioned and operate self-hosted LLM infrastructure on Linux VPS and ARM64 cloud instances — remote RAG SQL endpoints and an OpenAI-compatible local LLM query API, built on Ollama, llama.cpp, and Node.js.
  15. Design Systems & Creative Front-End

    • Author and maintain personal design systems (Hummingbird Design, MONO) applied across web, Electron desktop, and Android (Jetpack Compose) applications — token architectures and hand-written CSS with zero utility-framework dependencies.
    • Built advanced WebGL/Three.js experiences — procedural 3D generation, vertex and fragment shaders, custom post-processing chains (depth of field, god rays, CRT), and real-time audio visualisation with the Web Audio API.
    • Publish and maintain the shared ESLint configuration @tuomashatakka/eslint-config on npm.

Disciplines

Three lenses, one engineer

AI-native engineering, front-end & design systems, and creative code — swipe through.

How I Work

Build · Design · Direct

Three things I do, distilled into three plain promises.

Open Source & Experiments

Repositories & pens

Tools, plugins and studies — the public GitHub and CodePen output behind the products above.

Beyond Code

Graphics, illustration & photography

Vector illustration, print & icon design, and photography — selected pieces from Behance and Flickr.

Contact

Let's build something.

Hiring, collaborating, or just curious?