Maciej Wiatr, AI Product Engineer

Maciej WiatrHi, it's me!

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

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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)

Own.
01 Own the whole stackI work on the backend and the interface, and I set up the deploys myself, so a feature never waits for a handoff between teams.
Listen.
02 Stay close to the businessI take requirements from the founders and talk to customers myself, so I know why a feature matters before I build it.
Measure.
03 Judge work by what it movedI 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.
Next.jsTypeScriptReactPythonFastAPIPostgreSQLAWS

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.

Next.jsFramerCloudflare WorkersSupabase

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.

PostHogGoogle Tag Managern8nPostgreSQL

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.
Claude CodeClaude DesignCursorGitHub ActionsVercelSentry

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.
ReactNext.jsNode.jsApollo GraphQLTailwind CSSBunReact RouterDockerPostHogPostgreSQLAnt DesignMetabase

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%.

RubyRailsPostgreSQL

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.

Node.jsExpress
Power AED finder 72 bpm

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 SercemAED defibrillator finder
Code4HelpEU-funded NGO initiative
Kolping PolskaFoundation 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.

PythonLangGraphXGBoostScrapyPrefect

Next: ▓█░█▒▓█.

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

ReactTypeScriptPythonFastAPIPostgreSQL
“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 KijkoWorked with me on the same teamOriginal recommendation

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)

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)

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 LinkedIn GitHub
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