Krystian Jońca · Full-stack & AI-agents engineer

Full-stack TypeScript engineer with four years of commercial experience and seven writing code. I take products from idea to production across the whole stack: React and Vue front ends, Node, Hono and Effect back ends, and AI features on the serverless edge. Four of my side projects are live: a Polish classifieds marketplace, an open-source CLI on npm, a poker app for web, iOS and Android, and an AI audiobook SaaS. By day I work on an AI research platform for scientists. My engineering thesis was a serverless AI agent. I work with agentic tooling day to day: Claude Code, custom agent skills, and MCP.

Experience

Jul 2026 – Present

Senior Full-stack TypeScript Engineer · Tooploox

Full-stack and AI-agent work on an AI research platform, front-end to back-end.

AI platform for scientists Apr 2026 – Present · current

Full stack on an AI research platform for scientists, across the front end, the API behind it, and the agent workflows.

React · TypeScript · Tailwind · shadcn/ui · Plate.js · Effect · Mastra · AI SDK · GraphQL · Postgres

Jan 2023 – Jun 2026

Full-stack TypeScript Engineer · Tooploox

Owned features end-to-end across a sequence of client products over three and a half years.

AI onboarding agent Jan – Apr 2026

Full-stack on an AI onboarding agent for a global fashion brand. Took the agent pipeline from prototype to production: shorter response times, fewer failures, and something the client could run daily.

React · TypeScript · Tailwind · Python · OpenAI Agents SDK

Editorial content platform Sep 2022 – Dec 2025

Owned features end-to-end on an editorial content platform for about three years. Built the document editor and other core tools, kept the app responsive as the datasets grew, made the test suite fast and reliable, prototyped a more secure sign-in, and mentored new joiners.

Vue 3 · TypeScript · TanStack Query · Pinia · Tailwind · Storybook · Vitest · Playwright · Python · Sentry

Jul – Dec 2022

Junior Full-stack TypeScript Engineer · Tooploox

First six months: built a back end from scratch, then joined the editorial content team.

Crypto ↔ fiat conversion platform Jul – Sep 2022

Built the REST API from scratch for an early-stage startup: authentication, the core endpoints, and the PostgreSQL data model.

NestJS · TypeScript · Redis · PostgreSQL

Selected work

przydrodze.pl

Live · classifieds marketplace

Classifieds for the bulky local goods, services and rentals Poland advertises with a roadside SPRZEDAM sign.

Built alone over a month: buyer search, the seller publishing flow, phone sign-in, quotas, reports and donations, on the web and in a native app over one shared API contract.
Listings are free and capped per person, which keeps dealers out without a moderation team. Location is approximate by default and the exact pin is never stored. Any listing renders server-side to a printable sheet: a windscreen card, a tear-off notice, or a board tiled across A4.

TypeScript · React 19 · TanStack Start · Expo · Effect · Drizzle · PostgreSQL / PostGIS · Meilisearch · pdf-lib · Stripe · Telnyx · Cloudflare R2 / Turnstile · Docker · Dokploy

przydrodze.pl (przydrodze.pl)

Poker Night

Live · web + iOS/Android

Schedule home-poker games, track scores, and settle up, on web and mobile.

One TypeScript codebase for the web app, the iOS and Android app and the API, live in both stores, with scores syncing in real time between the devices at the table.
Settlement is a greedy algorithm that clears every debt in the fewest payments. Game recaps and play-style profiles are generated after each night.

TypeScript · React 19 · TanStack Start · Expo · Hono · Cloudflare Workers / Durable Objects / Hyperdrive / R2 / Queues / Workers AI · Postgres · Drizzle · Pulumi

pokernightapp.com (pokernightapp.com) App Store (apps.apple.com/…/id6760563257) Google Play (play.google.com/…)

Lektorek

Live · AI SaaS

Turn any document into a Polish or English audiobook. Pay per file.

Extracts text from PDFs, Office files and scans, runs it through neural TTS, and returns an MP3. Pages are sampled to price each file before checkout, so the quote is exact.
Pay per file rather than a subscription. A job that cannot be finished refunds in proportion to what was delivered.

TypeScript · Go · React 19 · TanStack Start · Effect · Cloudflare Workers / Workflows / Durable Objects / Containers / D1 / R2 · Gemini · Azure Speech · Stripe

lektorek.pl (lektorek.pl)

lnai

Open source · npm

One unified .ai/ config, synced to every AI coding tool.

Rules, skills, MCP servers and permissions are defined once in .ai/, then exported to Claude Code, Cursor, GitHub Copilot, Codex and four other tools, with per-tool overrides.
The sync is idempotent, so re-running it against a repository is safe. Open source, published on npm.

TypeScript · Turborepo · pnpm · Zod · commander · tsup · Vitest · Astro

lnai.sh (lnai.sh) npm (npmjs.com/package/lnai) GitHub (github.com/KrystianJonca/lnai)

Argus

BEng thesis

A serverless AI agent that monitors new scientific publications for you.

A standing query watches arXiv, OpenAlex and Semantic Scholar, ranks what is new against it, and sends a push notification on a match.
My engineering thesis. The agent writes and runs its own code in a sandbox instead of calling fixed tools, and each standing query owns its schedule, history and conversation.

TypeScript · Cloudflare Workers / Durable Objects / Agents SDK / Vectorize / Workers AI · Code Mode · Hyperdrive · Neon

argus.kjships.com (argus.kjships.com) Warsaw University of Technology

Skills

Languages

TypeScript · JavaScript · Python · Go · SQL

Frontend

React 19 · Vue 3 · TanStack Start / Query / Router · Tailwind · Expo · Storybook

Backend & data

Node.js · Hono · NestJS · Effect · Drizzle · REST / WebSockets · PostgreSQL / PostGIS · Meilisearch · SQLite / D1 · Redis · Neon

Cloud & edge

Cloudflare Workers · Durable Objects · Queues · Workflows · R2 / KV · Workers AI · AWS · Pulumi

AI & quality

LLM apps · RAG · “Code Mode” · OpenAI Agents SDK · Gemini · Azure Speech · Vitest · Playwright · CI/CD

Agentic engineering

Claude Code · custom agent skills · MCP servers · AGENTS.md / CLAUDE.md workflows

Education

2022 – 2026

BEng, Applied Computer Science

Warsaw University of Technology (Politechnika Warszawska)

Thesis: Argus (see Selected work), defended September 2026.