Senior Software Engineer
Software from the databaseto the interface.
I build backend systems, web applications and AI features, and I run them myself. In software development since 2016, most recently inside the teams of two US clients.
Available now. Permanent or freelance, 100 % remote.
- 2016
- Developing software since my apprenticeship began
- 11,000+
- automated tests in pytest and Jest
- 4
- own products in live operation
- 2
- US teams I worked in from 2024 to 2026
One request, six layers, one developer.
A request travels from the interface to the database and back. I work in every one of these layers, and I know the seams between them, where most failures begin.
Interface
Web frontends with Server Components, 3D elements and a focus on Core Web Vitals and technical SEO. Mobile apps with local storage and localization.
- React
- Next.js
- TypeScript
- Tailwind CSS
- Three.js
- React Native
- Expo
Server and APIs
Stateless services with streaming, webhooks and authentication. Integrations with partners and payment providers, hardened against limits, outages and duplicate calls.
- Python
- FastAPI
- asyncio
- Node.js
- REST
- WebSockets
- OAuth 2.0
- JWT
- Stripe
Data
Data models with schema design, indexes, migrations and row-level access rules. Vector search for retrieval, local databases for apps.
- PostgreSQL
- Supabase
- Row Level Security
- pgvector
- SQLite
AI
Multi-stage processing chains with structured outputs, cost caps and quality measured against a gold set. RAG, agents, vision and real-time voice AI.
- Anthropic Claude
- OpenAI GPT
- JSON Schema
- Pydantic
- RAG
- Agents
- Evaluation
- Voice AI
Quality
Tests are part of development, not an afterthought. Every production failure becomes a test case, and coding agents only work against acceptance tests.
- pytest
- Jest
- Vitest
- ruff
- ESLint
- Code review
Operations
Delivery and operation on my own Linux servers, with automatic TLS, CDN and deployments through the pipeline.
- Docker
- Linux
- Caddy
- Cloudflare
- Hetzner
- GitHub Actions
Experience
Three years of apprenticeship in a software company, then a decade in which I almost always owned the entire technology.
Own products
04/2025 to 08/2026
Software engineer, backend and AI applications (freelance)
Projectivity Inc., Silver Spring, MD, USA, remote in the team of an IT consultancy
- Multi-stage LLM processing chains in Python with Claude and GPT that ran in production in client projects.
- Made model outputs machine-reliable: JSON Schema, Pydantic validation and null values instead of invented data.
- Protected operations against provider limits and cost overruns, checked every change against a gold set before adoption, and delivered everything as FastAPI services in Docker.
Python, asyncio, FastAPI, Pydantic, PostgreSQL, Docker, GitHub Actions
09/2024 to 02/2025
Software engineer, backend and LLM integration (freelance)
Develop Zen, Richmond, VA, USA, remote in the team of a SaaS provider
- Integrated language models into existing Python applications, returning answers as fixed data structures instead of free text.
- Prompt and context engineering with versioned prompts so that runs stay comparable.
- Collected web data with Playwright and BeautifulSoup and checked images with OpenCV and PIL.
Python, Pydantic, JSON Schema, Playwright, BeautifulSoup, OpenCV
2025 to present
Software engineer, own products and client projects
Self-employed, Oberschleißheim, remote
- Development and operation of several own SaaS products and platforms as sole owner, from the data model to deployment.
- Websites for business clients in legal services, healthcare services and management consulting, multilingual and prepared for search engines.
- AI-native development with coding agents working in parallel, backed by over 11,000 automated tests.
Next.js, React, TypeScript, Python, PostgreSQL, Supabase, React Native, Docker, GitHub Actions
01/2022 to 08/2024
Founder and owner, sole technical responsibility
Own online retail, automated, Munich, remote, alongside a physical store
- Designed, built and ran the entire retail system alone: an extensive Python codebase of several background services for listing, orders, shipping, customer communication and monitoring, running continuously.
- Product listing as a multi-stage pipeline: normalise supplier data, generate texts and attributes through language model APIs, assign the category and publish only after passing validation. Missing details went to a review list instead of being filled in by the model.
- Image selection with a vision model, duplicate products detected through perceptual image hashes.
- Order processing through to the tracking number, designed to be idempotent so no order is placed twice.
- Shared interface layer for several sales channels and suppliers, with its own authentication, token renewal and rate limit per provider.
- Language model reply drafts for customer enquiries, special cases for approval. Watchdogs, logging and counters per account and channel.
Python, asyncio, SQLite, LLM APIs, vision models, REST, OAuth 2.0, Linux
11/2019 to 12/2021
Founder and owner, sole technical responsibility
Own online retail, Munich, remote
- Developed and maintained the technical foundation alone, with automated handling of orders and shipping through partner and supplier interfaces.
- Implemented automatic reconciliation of order and shipping data in continuous operation, with token renewal without manual intervention.
- Regularly reconciled supplier product, price and stock data so nothing sold out was ever sold.
- Kept orders, products and shipments in an SQL database and analysed them with SQL, running on my own Linux server with scheduled jobs.
Python, REST, OAuth 2.0, SQL, Linux, cron
09/2016 to 08/2019
IT Specialist in Application Development (Fachinformatiker)
Crealogix, Puchheim, Apprenticeship at a software company, final grade 1.8 (German scale, 1.0 is best)
- Java, JavaScript, Angular and SQL, database design, tests with JUnit and Jasmine, Git and Scrum. Also internal training sessions for apprentices.
Java, JavaScript, Angular, SQL
Method
The model describes, the code decides.
Generated content only refers to existing records. The program makes the selection.
What code can check, no model checks.
Mechanical rules run before any model-based evaluation.
State lives in the database.
Services stay stateless and can restart without losing anything.
Every production failure becomes a test case.
That way the same breakdown is never built twice.
About me
I am a software developer from Oberschleißheim near Munich. After my apprenticeship at Crealogix I spent five years responsible for the entire technology of two businesses of my own, and learned the whole craft there, from the data model through integrations to operations.
Since 2024 I have worked on production AI applications and built products of my own on the side. I am looking for work in which I own a system across several layers, as an employee or as a freelancer.
Tell me what you want to build.
info@akayguen.devA short email is enough. I send my resume as a PDF on request.