AI Product Studio · Berlin

Breuer Land
Studios

Products built with strategy. Shipped with AI.

I'm Mariel Breuer, a product manager who doesn't just vibe-code — I define problems, write specs, build phased roadmaps, and then build fast. Every product here started with a brief, a user, and a reason.

📋 Clear problem definitions 🗺️ Prioritized roadmaps 🚀 AI-assisted execution 📦 4 products live

How I work

Strategy first,
then build.

Every product here started with a brief, not a blank file. The AI is the accelerant — the thinking is still PM work.

01

Problem Definition

Who is the user? What's the core job to be done? What makes this worth building? No code until this is solid.

02

Scope & Spec

Feature lists, user flows, and a written product brief. Decisions are made before development begins, not during.

03

Phased Roadmap

Prioritized phases with dependencies and milestones. Nothing sits in a vague "someday" pile — it has a place in the plan.

04

AI-Assisted Build

With strategy locked, AI handles the execution velocity. Prototype → iterate → ship, without a team of five.

The portfolio

4 Products.
4 Problems Solved.

Take-home 3.842 €
ESt + Soli
−612 €
TK + PV
−746 €
Q2 VAT due Jun 10 21 days
✓ Live Finance Tool

Steuer Tracker

"Tax clarity for German freelancers — no Steuerberater required for the basics."

A browser-based tax calculator built specifically for German freelancers. Track monthly income and expenses, estimate Einkommensteuer and TK health insurance, monitor quarterly VAT deadlines — all in one file, with no data ever leaving your device.

Monthly income & expense log · Home office Tagespauschale (6 €/day)
Income tax estimate · Steuerklasse 1 & 2 · Solidaritätszuschlag
TK KV + Pflegeversicherung · Beitragsbemessungsgrenze cap & floor
Quarterly VAT Voranmeldung · Upcoming payment deadline tracker
Built with: Pure HTML · CSS · Vanilla JS · localStorage · No backend · No login required
Open Calculator →
Calendar Land screenshot
🔒 Invite Only Productivity

Calendar Land

"The calendar app built for how a freelance PM actually works."

A full-featured productivity app combining calendar, tasks, kanban, smart scheduling, and multi-user auth — built from scratch in Next.js with PostgreSQL. Built because no existing tool had exactly what a freelance PM needs.

Day/Week/Month views · Recurring events · Drag & drop · Conflict detection
Tasks & Kanban board · Task-to-calendar drag scheduling
Public booking pages · Multi-user auth · Browser push reminders
Coming: time tracking, AI agent, calendar sync, Telegram bot
Tech: Next.js 15 · React 19 · TypeScript · PostgreSQL · Prisma · Tailwind 4 · Zustand · TanStack Query
Request Access → View Roadmap
EIA screenshot
✓ Live Social Impact

EIA

"Named after a woman who started over. Built for women who are starting forward."

EIA is named after the founder's grandmother — a woman who fled WWII and rebuilt her career in her 40s as a sociologist. The app helps women in tech facing compounded barriers (displacement, career gaps, restrictive environments) break into the international remote market. Safely.

AI-guided conversational assessment of skills, background & goals
Remote Work Readiness Score across 5 dimensions with action plans
Privacy-first portfolio builder — anonymous by default, safe-share links
Warm AI persona: "you're closer than you think"
Tech: Lovable · Claude API (Anthropic) · RTL-ready layout · No login required to start
Try EIA →
Loca Land screenshot
✓ Live Indie Game

Loca Land

"Feed your friends. From Berlin to Warsaw, one pixel at a time."

A retro pixel-art platformer starring Loca, a black cat on a mission. She travels 800km from Berlin to Warsaw across 13 chapters and 4 seasons — collecting food, feeding shelter friends, facing enemies, and finding allies along the way.

13 chapters across real cities: Berlin → Magdeburg → Wrocław → Warsaw
4 seasons (Summer, Fall, Winter, Spring) · Boss fights at each end
Core loop: Explore · Collect · Overcome · Feed
Retro pixel aesthetic · Cozy but progressively challenging
Built with: Lovable · AI-assisted pixel art, level design & game logic
Play Loca Land →

The tools are new.
The craft is not.

AI lets me build products that would have taken a team of five. But the thinking that makes them worth building — that's the same work it's always been.

Good products start with honest problem definitions, real tradeoffs, and a clear answer to "why does this matter?"

That's what you'll find in everything built here.