Selected work

Projects built to solve real problems

A selection of backend systems, AI experiments and full-stack products. Each project includes the decisions, constraints and evidence behind the implementation.

Projects

Java, TypeScript

todrawn.com

case study

Problem: For the board mode, keep drawing and board state in sync across connected clients while the wider product also supports Scribe, accounts and subscriptions.
Role: Built todrawn.com end to end; this case study focuses on the Spring Boot API, Next.js canvas experience, real-time layer, billing and deployment behind the board mode.
Decisions: WebSockets carry board updates; PostgreSQL stores durable data; Redis handles fast, short-lived state; Docker, GitHub Actions and Cloud Run handle delivery.
Result: A live todrawn.com product combining Scribe with collaborative boards, including a production board mode with Stripe subscriptions.

Java

LlamaTalks

case study

RAG PIPELINE grounded response

01 Document Tika → chunks
02 Vector store embeddings + retrieval
03 Ollama context + history
04 SSE Reactor/Flux

Problem: Answer questions from a user's documents while keeping the language model local to the application.
Role: Built a Spring Boot chatbot around LangChain4j, Ollama, document ingestion and persistent conversations.
Decisions: The ingestion endpoint sends files through Apache Tika parsing and chunking, then embeddings and semantic retrieval provide context alongside conversation history. LangChain4j connects that context to Ollama, while Reactor/Flux and SSE stream the response; changing embedding dimensions requires re-ingestion.
Result: An open-source chatbot project with local-model conversations, document Q&A and streamed responses.

Java, React

Gamelog

case study

Problem: Give players one place to organize a game library, track progress and keep social features beside the backlog.
Role: Built a full-stack game backlog manager with a Spring Boot API and React interface.
Decisions: A Kanban dashboard models progress; PostgreSQL persists accounts and library data; Redis provides caching; Docker packages the application.
Result: A working full-stack tracker with search, playtime, ratings, friend requests and a live demo.

Java, Vue, TypeScript

MapGenerator

case study

Problem: Turn one seed and a map size into an explorable fantasy world while keeping large maps responsive in the browser.
Role: Built the Spring Boot generation backend and Vue/TypeScript Canvas client, including the streaming path, viewport and renderer.
Decisions: Multiple noise layers model height, moisture, temperature and the continent mask. The client uses a hybrid virtual/offscreen canvas: static land is pre-rendered and only waves are calculated per frame.
Result: A working procedural map generator with streamed terrain, pan/zoom navigation, topology shading, procedural textures and cities.

Java, Angular

Cibaria

case study

Problem: Give recipe enthusiasts one place to create, store, search and share recipes with a bilingual interface.
Role: Built the full-stack application across its Angular frontend and Spring Boot REST API, connecting the product to PostgreSQL.
Decisions: Angular 18.2.7 provides the responsive client, Spring Boot 3.4.1 exposes the API, PostgreSQL persists recipe and user data, and the product keeps English and Polish content paths together.
Result: A live recipe manager with recipe creation, search, filtering, profiles, favorites, ratings and English/Polish support.

Astro, TypeScript

SosniakPortfolio

case study

Problem: Present Sebastian Sośniak's projects and experience in a fast portfolio that stays easy to maintain as the content grows.
Role: Designed and built the portfolio with Astro, TypeScript and Tailwind CSS, then deployed it to the live metricmind.pl domain.
Decisions: Astro's mostly static output keeps the content path light; TypeScript supports type-safe components; Tailwind CSS keeps the visual system consistent; Vercel provides hosting and delivery.
Result: A live content-first portfolio for Sebastian Sośniak at metricmind.pl, backed by a public repository with 10 commits.

Astro, TypeScript

StrefaSA

case study

Problem: Connect an MTA:SA community's game atmosphere with a credible web presence and a shop path that hands checkout to the separate backend.
Role: Worked as co-owner and co-creator of the server, designing and building the Astro frontend, including the marketing site and /sklep handoff.
Decisions: Astro keeps the public frontend lightweight; live server data builds trust; /sklep hands payment flow to a separate MTA backend and Stripe Checkout instead of pretending the frontend owns fulfillment.
Result: A live cinematic marketing site and store entry point at strefasa.pl, backed by a private repository with 26 commits.

See more on GitHub Browse the public repositories and implementation details.