Software development
Web apps and APIs with TypeScript, React, Next.js and Node.js.
- From MVP to scaling product
- Clean, testable codebase
- Hands-on team reinforcement
Available
Software development · Architecture · AI integration
Freelance software developer & architect for AI integration – Hamburg & remote
I'll specialize in whatever it takes to solve your problem.
I'm Kjell Otto, a freelance software developer and architect based near Hamburg, Germany. For 19 years I've built web applications, cloud platforms and – increasingly – AI integrations that hold up in your team's day-to-day work.
On-site in Hamburg & Rotenburg (Wümme) · remote across DACH
- years of experience
- 19+
- projects
- 20+
- industries
- 4
- Working mode
- Remote + on-site
services
What I do for you
Three focus areas, one standard – software that works in production and moves your team forward.
Software architecture
Sound cloud architectures and a path away from the legacy monolith.
- Architecture reviews & ADRs
- GCP, AWS, Kubernetes, IaC
- Modernising .NET, Java and Go systems
AI integration
Use AI where it creates measurable value – inside your existing software.
- LLM integration (Claude, OpenAI)
- RAG over your own documents & data
- Agents, automation, evaluation
skills
Skills & technologies
Honest tiers instead of percentage bars: core skills I use daily, strong skills regularly in projects, familiar topics well enough to integrate them sensibly.
- Core
- Strong
- Familiar
AI integration
9
- AI agents & tool use – Core
- LLM APIs (Claude, OpenAI) – Core
- Model Context Protocol (MCP) – Core
- Retrieval-Augmented Generation (RAG) – Core
- Evals & quality measurement – Strong
- Cost & latency optimisation – Strong
- Vector search (pgvector) – Strong
- Fine-tuning – Familiar
- Self-hosted / on-prem models – Familiar
Web & product
8
- Next.js – Core
- Node.js – Core
- React – Core
- TypeScript – Core
- REST & GraphQL API design – Strong
- Astro – Strong
- Testing (Vitest, Playwright) – Strong
- React Native – Familiar
Cloud & platform
8
- Google Cloud (GCP) – Core
- Kubernetes – Core
- Terraform / IaC – Core
- AWS – Strong
- CI/CD – Strong
- Observability – Strong
- Azure – Familiar
- VMware vSphere (SDK) – Familiar
Architecture & backend
8
- Software architecture – Core
- Domain-Driven Design – Core
- Microservices – Core
- Legacy modernisation – Core
- .NET / C# – Strong
- Go – Strong
- Java / Spring – Strong
- Event streaming (Kafka) – Familiar
projects
Selected projects
Context, approach, result – a look at real projects.
Revenue and royalties reporting (Engel & Völkers)
TypeScript front end and backend work on a royalties and revenue reporting tool that handles millions in revenue every year.
- TypeScript
Frontend lead for the launch of a mobility startup (MOIA)
Senior front-end engineer and team lead while building a deep-tech mobility startup – pragmatic, product-driven, milestones reached ahead of deadlines.
- TypeScript
process
How we work together
Arrive on-site first, then deliver efficiently remote – anywhere in Germany and the DACH region.
- 01
Intro call
30 minutes, free – goals, scope and whether we're a good fit.
- 02
On-site onboarding
A few days with your team to learn people, systems and domain.
- 03
Remote delivery
Mostly remote, with fixed rituals and visits as needed.
- 04
Handover & enablement
Documentation and knowledge transfer – your team takes over.
feedback
What clients say
“I've had the pleasure of working with Kjell, a senior software engineer, for the past year and a half on a mission-critical revenue reporting tool that brings in millions of dollars in revenue yearly. Kjell is an extremely capable frontend/TypeScript engineer with an equally solid understanding of the backend.”
“His constant push for moving forward with features and releasing them to the users to gather their feedback was invaluable to our project’s success.”
“Kjell is the right guy you will want at your side when you are launching a deep tech startup like we did together at MOIA. Kjell is a builder and craftsman in the best possible sense.”
“Kjell expertly filled the roles of Senior Front-end Engineer and Team Lead during our assignment at a rapidly growing mobility company. His pragmatic approach and lean-oriented product instincts were key in guiding a team of front-end developers, maximizing business value for the company and reaching milestones well before any deadline.”
region
In Hamburg, Rotenburg (Wümme) and remote
I work from the Hamburg and Rotenburg (Wümme) area – anywhere between the Elbe and the Weser I can be on-site quickly. For teams elsewhere in Germany, Austria and Switzerland I start with an on-site onboarding and then work mostly remotely. We'll always find a way.
faq
Frequently asked questions
Do you work outside Hamburg and Rotenburg?
Yes. After an on-site onboarding I work mostly remotely, across Germany and the DACH region. We'll always find a way.
What engagement models do you offer?
Time and materials (daily or hourly), fixed price for well-defined packages (e.g. an architecture review or an AI prototype), and reinforcement of existing teams.
How do I start an AI project without much risk?
With a short discovery workshop and a focused prototype against real data, including success criteria. Only once the value is proven do we scale.
How do you handle data protection with AI?
Data flows are clarified up front. Where needed I use EU hosting and providers with a data processing agreement that don't train on your data.
How soon can you start?
That depends on my current workload – a short message is enough, I reply within 1–2 business days.
Which languages do you work in?
German and English – in meetings, documentation and code.
contact
Let's talk about your project.
Tell me briefly what it's about – I'll get back to you within 1–2 business days.