# Maciej Wiatr, AI Product Engineer

> Maciej Wiatr, AI product engineer in Kraków. Built Mimira's AI tender search platform from first MVP to 300+ client companies. I design it, build it, ship it.

Page: https://maciejwiatr.com/ · pl: https://maciejwiatr.com/pl/home.md

AI product engineer. I design it, build it and ship it, from first commit to *300+ client companies*.

## What I've built, and *how I work*.

The sections below are my experience: products I've shipped at Mimira and SonarHome, my research, and earlier work for NGOs. Before you scroll, here is how I approach the work.

**1st place**, AI KrakHack (June 2025)

- **01 Own the whole stack**: I work on the backend and the interface, and I set up the deploys myself, so a feature never waits for a handoff between teams.
- **02 Stay close to the business**: I take requirements from the founders and talk to customers myself, so I know why a feature matters before I build it.
- **03 Judge work by what it moved**: I judge a feature by the number it moved, like clients won or hours of manual work saved. When nobody measures that yet, I build the tracking too.

## Mimira, from MVP to *300+ companies*.

I owned and built the full stack of Mimira's AI-driven tender search platform, from the first MVP to more than 300 client companies, including Orlen, Żabka, iSpot, Inea and Uniqa.

- Designed the core backend architecture on AWS, Python, FastAPI and Postgres.
- Managed a team of three developers for several months, taking requirements straight from the founders and coordinating work across departments.
- Spoke directly with customers and gave them technical support.

Stack: Next.js, TypeScript, React, Python, FastAPI, PostgreSQL, AWS

## *200,000* indexed tender pages.

I built an SEO-driven tender directory with around 200,000 indexed pages. It now brings in a significant share of inbound leads, from organic search and paid campaigns alike.

Stack: Next.js, Framer, Cloudflare Workers, Supabase

## Every lead, *attributed*.

I built the user-attribution pipeline, offline conversions included, and the marketing department's main lead-distribution dashboards, so every lead can be traced from its first click to the salesperson who closes it.

Stack: PostHog, Google Tag Manager, n8n, PostgreSQL

## Owning the interface, and *how it gets built*.

As lead full-stack engineer I owned UX across the platform: I designed every in-app interface and landing page, and built the frontend for every ticket.

- Cut UI iteration time several-fold by prototyping multiple UX versions per round in Claude Design.
- Built internal Claude Code skills for frontend and UI work, and defined the team's frontend code-quality rules.
- Set up CI/CD on GitHub Actions, Sentry in every project and Vercel preview deployments, so each ticket was checked before reaching production.
- Co-defined the bug-handling process: error statuses, ticket triage and prioritisation.

Stack: Claude Code, Claude Design, Cursor, GitHub Actions, Vercel, Sentry

## SonarHome, pricing *every flat* in Poland.

At Poland's largest property valuation portal I developed and optimised full-stack real estate applications, and led the frontend refactor of Lead360, the market-analysis app.

- Led frontend technology strategy, introducing Bun, React Router v7, the latest Next.js and feature-based design.
- Analysed user data with PostHog, Google Analytics, Metabase and PostgreSQL.
- Led recruitment and onboarding for new software engineers.

Stack: React, Next.js, Node.js, Apollo GraphQL, Tailwind CSS, Bun, React Router, Docker, PostHog, PostgreSQL, Ant Design, Metabase

## Invoicing with *80% less* manual work.

I designed and deployed an invoicing system in SonarHome's Ruby on Rails backend that cut the manual work behind every invoice by more than 80%.

Stack: Ruby, Rails, PostgreSQL

## *200,000* emails a month.

I engineered SonarHome's main email service in Node.js and Express. It processes more than 200,000 emails every month.

Stack: Node.js, Express

## Code that had to work *for strangers*.

Earlier projects for NGOs and foundations, where the user is someone who needs help right now.

- **Ratuj z Sercem**: AED defibrillator finder
- **Code4Help**: EU-funded NGO initiative
- **Kolping Polska**: Foundation portal

## Agents that *read* the rental market.

My engineering thesis: a multi-agent LLM system for real-estate search and rental price extraction. The research continues as a part-time master's in Applied Computer Science at UJ FAIS from October 2026.

Stack: Python, LangGraph, XGBoost, Scrapy, Prefect

## *Next:* a company I can't name yet.

From November 2026, senior fullstack engineer on an AI-first team.

Stack: React, TypeScript, Python, FastAPI, PostgreSQL

> “Maciej is an absolute master at bridging core IT engineering with cutting-edge AI tools. The velocity at which he turns complex ideas into fully working, high-quality solutions would have honestly felt like science fiction just a few years ago.”
>
> — [**Pawel Kijko**](https://www.linkedin.com/in/pawel-kijko/) · Worked with me on the same team · [Original recommendation](https://www.linkedin.com/in/maciej-wiatr/details/recommendations/)

## Away from *the keyboard.*

### Japan, and the road there

Weekly Japanese lessons and a long trip in the plans. Travel is how I reset and come back with better ideas.

### Powerlifting

Squat, bench press and deadlift. I log every session, and progress shows up as kilos on the bar.

### Dungeons & Dragons

Rolling dice with friends. The best practice there is for improvising when the plan meets reality.

## Topics I *keep digging into*.

Two subjects I keep coming back to. Each one has its own page, in Polish.

### [Agent-readable websites (in Polish)](https://maciejwiatr.com/pl/strona-czytelna-dla-ai)

How to make sure AI agents (ChatGPT, Claude, Perplexity) get the full content of a website: llms.txt, a Markdown version at the same URL, and tests that check it.

### [AI agents and browser automation (in Polish)](https://maciejwiatr.com/pl/agenci-ai-krakow)

AI agents that do the work in the browser and in company tools: they fill in forms, collect data and get through admin panels without anyone clicking by hand.

## Send me a *fax*.

Write on the page and press the green button. Your mail app opens with the message addressed to me.

- [maciej.wiatr00@gmail.com](mailto:maciej.wiatr00@gmail.com)
- [LinkedIn](https://www.linkedin.com/in/maciej-wiatr)
- [GitHub](https://github.com/MaciejWiatr)

Maciej Wiatr, Kraków · [Home](https://maciejwiatr.com/) · [Blog](https://maciejwiatr.com/blog) · [Projects](https://maciejwiatr.com/projects) · [Agent-readable checker](https://maciejwiatr.com/agent-readable-check) · [LinkedIn](https://www.linkedin.com/in/maciej-wiatr) · [GitHub](https://github.com/MaciejWiatr) · [This page as markdown](https://maciejwiatr.com/home.md)