~hey, I'm Stefan Trost_

I build AI & automation systemsthat actually ship.

Senior Fullstack Developer & AI Engineer

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case_studies

Three engagements, in depth.

The actual problem, the decisions that mattered, the stack picked and why, and the measurable outcome.

Confidential · NDAFeb – Apr 202610 weeks

Rebuilt a 32k-user no-code platform with 5M+ records in 8 weeks.

Full rebuild from Bubble to a custom Next.js stack, plus two weeks of aftercare.

8 wks
rebuild to live migration
32k
active accounts migrated
5M+
records migrated, verified
100%
Stripe continuity

Context

The platform had run on Bubble for over two years: 32,000 accounts, 5M+ records, and so much no-code logic that every new feature risked breaking something else. The founders wanted to build more AI features, but Bubble meant wiring everything by hand, with no real code to build on. So they decided to rebuild. The timeline was tight: the new platform had to be live within eight weeks.

This would normally be a whole team's job, but I did it on my own. I started with the business rather than the code, so I first had to understand what the product does and how the company makes money. Then I went through the existing system: the architecture, the database, and all the Bubble workflows. None of that existed as code, so normally you'd have to click through every workflow by hand just to understand it. Instead I built my own AI tools and connectors that could read the Bubble logic directly, which turned weeks of manual analysis into days. From there I designed a new database schema and data model from scratch, and set up a proper design system in Storybook before I started building. After the platform went live, I spent another two weeks on cleanup, bug fixing, and support.

Challenges

  • Full-team scope, one engineer
    Audit, data-model redesign, backend, frontend, a design system, and a live migration. That's normally several specialists. Here it was one person, in sequence, on a tight deadline.
  • Live production data
    5M+ records, active Stripe subscriptions, and live login state all had to move over without any downtime. No room for failure, no margin for losing data.
  • Undocumented Bubble logic
    Bubble workflows aren't code. Every rule lived in a visual editor, with no docs and nothing worth exporting. Normally you'd have to click through every workflow by hand just to work out what it does.

Key decisions

  • Next.js App Router + Supabase
    Server Components for catalog pages, Supabase for auth + Postgres to mirror Bubble's data model without an impedance mismatch.
  • AI-assisted analysis
    Instead of reverse-engineering everything by hand, I built custom AI tooling early to read the Bubble logic and turn it into specs. Work that would have taken weeks was done in hours, and the whole analysis was finished in a week.
  • Staged migration
    Custom scripts to extract live Bubble data, transform it into the new schema, and load it into Postgres, tested in batches before the DNS swap.

Stack

  • Next.js App Router
  • React
  • TypeScript
  • Tailwind CSS
  • Supabase
  • PostgreSQL
  • Prisma
  • Drizzle
  • better-auth
  • Stripe
  • AI Workflows
  • Claude
  • LLM
  • MCP
  • GitHub Actions
  • Vite
  • Turborepo
  • AWS
  • Serverless
  • TDD
  • Jest
  • Vitest
  • Vercel
process

How I work with teams.

A clear four-step engagement for teams that want senior execution without agency overhead.

01

Intro call

A 30-minute call to understand the problem and check if we're a fit. No pitch, no deck, just a conversation. If I'm not the right person, I'll tell you.

02

Planning

Starting with understanding the business and its strategy, then working out a matching IT strategy and architecture underneath before we start coding.

03

Build

Weekly increments you can see and try. I work, test, and deploy across proper environments throughout, with CI, tests, and observability from day one.

04

Ship

Production launch, runbook, handover docs. The code belongs to your team, no lock-in.

stack

Pragmatic stack.

The tools I build with.

ai_llm

AI & LLM

  • Claude API
  • OpenAI
  • LangChain
  • RAG
  • AI Agents
  • MCP
  • Portkey
  • pgvector
  • Machine Learning
  • TensorFlow
frontend_apps

Frontend & Apps

  • Next.js
  • React
  • React Native
  • Expo
  • EAS
  • TypeScript
  • JavaScript
  • Redux
  • Tailwind
  • shadcn/ui
  • Storybook
  • Vite
  • SASS
  • Angular
  • Svelte
  • Ionic
  • i18next
backend_data

Backend & Data

  • Node.js
  • tRPC
  • REST
  • GraphQL
  • Hasura
  • PostgreSQL
  • Prisma
  • Drizzle
  • Supabase
  • Firebase
  • Firestore
  • BigQuery
  • SQL
  • Python
  • Stripe
  • better-auth
  • NextAuth.js
  • Auth0
  • JWT
  • OAuth
cloud_devops

Cloud & DevOps

  • GCP
  • Cloud Run
  • Cloud Functions
  • AWS
  • Lambda
  • S3
  • EC2
  • IAM
  • CloudFront
  • API Gateway
  • DynamoDB
  • SQS
  • CloudWatch
  • CDK
  • SAM
  • Vercel
  • Docker
  • Kubernetes
  • GitHub Actions
  • CI/CD
  • Turborepo
  • Bitrise
  • Fastlane
testing_quality

Testing & Quality

  • TDD
  • Jest
  • Vitest
  • Cypress
  • Playwright
  • Detox
  • Testing Library
  • Unit Testing
  • E2E
architecture

Architecture

  • Multi-tenancy
  • White-labeling
  • System architecture
  • Serverless
  • Microservices
whoami

I take ideas all the
way to production.

I'm a fullstack developer based in Stuttgart, working across frontend, backend, mobile, and cloud.

I work across the whole stack: React, React Native, TypeScript, Node, AWS and GCP, plus the AI and RAG side. What I'm good at is keeping the overview and getting all the pieces to work together: a sensible architecture, real tests, a deploy pipeline that runs reliably instead of by hand, and code the next person can actually maintain and build on.

I work best with founders, startups, and small teams, where I can get properly involved and use everything I'm good at, not just one slice of it.

Based
Stuttgart, Germany · CET
Working since
2014 · self-employed
Working with
Founders & small product teams · EN / DE
approach

Why hire me for your next project.

Senior engineering focused on AI features, automation, and the fullstack systems that hold them together.

  • AI early adopter

    I've been working with AI since early on. With years of hands-on experience and a constant urge to optimize, I've built it deep into all of my processes. That lets me deliver at the same quality but at a speed usually only a whole team can manage.

  • I think along

    From business and IT strategy through architecture to building and shipping, I can cover the whole pipeline myself. I think along instead of just working through tickets, and I'll tell you when something should be done differently.

  • Transparent delivery

    Weekly increments you can see and try for yourself, so you always know what's being built and where it stands.

  • Code that lasts

    Documented architecture, typed code, solid test coverage. I hand over clean code that's maintainable and scalable.

testimonials

What some of my clients say.

He brings strong technical expertise and approaches problems in a very structured and pragmatic way. What I particularly value is that Stefan always thinks beyond the immediate task. He considers technical decisions in the broader product and business context and contributes ideas that genuinely improve the overall solution.
Kevin C. Bauer
Kevin C. Bauer
Geschäftsführer & Gründer, Blaulichtschule | LawGames GmbH
Dec 2025
Seine technische Expertise ist außergewöhnlich und zeigt sich in allen Bereichen, die er anfasst. Stefan verfügt über ein sehr tiefes Verständnis für komplexe Systeme und schafft es gleichzeitig, pragmatische und saubere Lösungen zu entwickeln. Besonders schätze ich, dass er nicht nur aus Entwicklersicht denkt, sondern stets das große Ganze im Blick behält — inklusive Produktlogik, Skalierbarkeit und zukünftiger Weiterentwicklung.
Julia Hückmann
Julia Hückmann
Senior E-Commerce Managerin
Dec 2025
I highly recommend working with Stefan. He fit right in and easily understood our complex setup with micro frontends. He contributed a lot of code and was able to automate our release process for us. Amazing work.
Stefanie Laharnar
Stefanie Laharnar
Engineering Lead
Jun 2024
Stefan delivered a robust and scalable foundation for our web app, which has become a vital part of our platform. His technical expertise, problem-solving skills, and team player attitude made him a true asset.
Mark Wightman
Mark Wightman
Founder, SaaS startup
Jan 2024
As Technical Lead, Stefan played a pivotal role in driving the team's success. His leadership in IT architecture and full-stack development was instrumental. He created a collaborative, learning-oriented environment.
Andrew Snyder
Andrew Snyder
Caster LLC, New York
Dec 2023
Stefan was extremely helpful in every step — he guided the development, helped troubleshoot, and built a GitHub repository for me to run the function on my own. Competent developer with a great work ethic.
John Belcher
John Belcher
BERP LLC | Detroit, USA
Feb 2024
Die Zusammenarbeit mit Stefan war stets eine Bereicherung. Er versteht es, komplexe IT-Probleme zu lösen und zukunftsweisende Lösungen zu bieten.
Emir Cuk
Emir Cuk
Senior Engineer
Jan 2023
Die Zusammenarbeit war immer hervorragend und zielführend. Er besticht durch profunde IT-Kenntnisse, unternehmerisches Denken und Problemlösungskompetenz.
Roland Trost
Roland Trost
IT Consultant
Mar 2023
contact

Have a system that should exist by now? Let’s scope it.

No pitch and no slide deck. Just a 30-minute call to understand the problem and see whether I'm the right fit. If I'm not, I'll tell you directly.

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