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Christian Worsch
Available for new projects

Software Architect & Senior Developer · Freelance

Cloud architecture, backend systems and GenAI integration that your team can build on.

I design and build scalable web platforms, cloud architectures and LLM integrations. In software development since 2017, freelance since 2025. I work hands-on in the code while thinking in systems: architectures that teams understand and keep extending, implemented by me together with them.

Experience
In software development since 2017, freelance since 2025
Focus
Python, TypeScript, PHP, Azure, Generative AI
Location
Wurmberg near Stuttgart, remote first
Languages
German (native), English (business fluent)

Services

What I can do for your project

Six areas where I deliver, from architecture to running code. Every engagement starts with a clear scope and ends with a solution your team can operate and extend.

Cloud architecture and multi-tenant SaaS

Design and implementation of multi-tenant platforms on Azure, including SaaS and bring-your-own-cloud operation, tenant resolution, infrastructure as code with Terraform and CI/CD for every environment.

  • Azure Container Apps
  • Terraform
  • Multi-tenancy
  • CI/CD
  • Docker

Identity, auth and security

Identity architectures with OIDC, backend-for-frontend patterns with HttpOnly cookies, token auth for machine clients and service-to-service authentication in distributed systems. Security hardening included.

  • OIDC
  • Zitadel
  • SuperTokens
  • BFF pattern
  • Key Vault

Backend and API development

REST APIs and microservices with FastAPI, Django, Laravel, Symfony or Node.js. Delivered with automated tests, CI/CD pipelines and documentation so your team can run the code without me.

  • FastAPI
  • Django
  • Laravel
  • Node.js
  • PostgreSQL
  • MongoDB Atlas

Generative AI and LLM integration

AI assistants and retrieval-augmented systems that work on your own data. Integration of Claude and OpenAI into internal processes, vector databases and enterprise sources such as SharePoint. Proven on an enterprise-wide GenAI platform at dmTECH.

  • Claude
  • OpenAI
  • RAG
  • pgvector
  • Qdrant
  • Chainlit

Industrial IoT and data pipelines

Sensor data ingest via MQTT, time series storage with regional data residency, workflow engines for data processing and dashboards that turn plant data into decisions.

  • MQTT
  • Time series
  • MongoDB Atlas
  • Prefect
  • Data residency

Enterprise integration and legacy modernisation

Connecting enterprise systems through middleware and integration APIs, data migration and step-by-step replacement of legacy systems without interrupting operations, including frontend migrations such as Angular to React.

  • Middleware
  • Data migration
  • Legacy modernisation
  • React
  • TypeScript

Case studies

Two projects in detail

What the situation was, what I did and what came out of it. Both delivered through Nuvus as external architect and lead developer. More stations in the timeline below.

Bosch

Multi-tenant digital twin platform for industrial plants

Software Architect and Lead Engineer, via Nuvus · 01/2026 to 10/2026

Challenge

Industrial customers model their plants as typed entities, connect live machine data over MQTT, IoT Hub or file drops, bind signals to assets and run analytics flows from a node-based flow editor. The platform had to be rebuilt as a product that runs both as SaaS and as a bring-your-own-cloud install on customer infrastructure, with a real identity model, regional data residency and infrastructure that can be reproduced from code.

Approach

  • Set up the new monorepo and owned architecture, infrastructure and core backend components as external architect, hands-on as the most active contributor.
  • Tenancy: one database per tenant with a tenant registry in SaaS mode, single-tenant Docker Compose install for BYOC, both served by a shared tenancy library.
  • Identity on self-hosted Zitadel with OIDC: one organisation per tenant with admin, member and viewer roles, branded login per tenant, idempotent tenant onboarding through a dedicated user management service, internal tokens between services.
  • Infrastructure as code with Terraform: one stack module per environment on Azure Container Apps, Service Bus, IoT Hub and Key Vault, private network with a single public proxy, secrets generated on first apply and never stored in variable files.
  • Data moved from Cosmos DB to MongoDB Atlas with regional clusters for data residency and native time series; Prefect 3 as workflow engine triggered by internal events.
  • Split ingest out of the flow engine into its own service with one adapter per source and certificate-based MQTT ingress with per-tenant client certificates. Frontend moved from Angular to React.

Outcome

  • SaaS and BYOC run from one codebase, tenant and developer onboarding are automated.
  • Network locked down to one public entry point with a fixed egress IP, Terraform drift ended, security hardening across proxy, API docs, secrets and service permissions.
  • Ingest path load-tested for more than ten thousand data points per second.
  • Architecture papers, decision records, reviews and mentoring, plus shared Azure DevOps pipeline templates with per-package releases, so the team can carry the platform forward.
  • Python
  • FastAPI
  • React
  • TypeScript
  • MongoDB Atlas
  • Azure
  • Terraform
  • Zitadel
  • MQTT
  • Prefect

WeDaVinci

User management, billing and video editor for an AI video platform

Senior Full-Stack Developer, via Nuvus · 08/2025 to 05/2026

Challenge

The product was being rebuilt from a collaborative ideation tool on Angular, Node.js and MongoDB into an AI video platform: users write a script, get a synopsis and a storyboard and generate AI images and videos per shot. The legacy user management could not carry subscriptions, credits or a login shared across the new services.

Approach

  • Designed and built a dedicated user management service with FastAPI and PostgreSQL as the central hub for authentication, users, subscriptions, credits and billing. The video backend only verifies sessions.
  • Authentication on SuperTokens with email and password plus Google sign-in, HttpOnly session cookies shared across the platform's subdomains, email verification and password reset.
  • Stripe checkout, customer portal and webhooks. Credit model with subscription credits per billing period and purchased credits with twelve-month expiry, reserved on request and confirmed or refunded afterwards, because a video generation can run for more than twenty minutes.
  • Built the React storyboard and video editor: scene and shot playback, reordering, trimming, versioned variants, image-to-video, PDF and ZIP export.
  • Structured JSON logging with redaction of sensitive data, Alembic migrations for both Python services, test suites for credits, payments, plans and admin functions.

Outcome

  • Legacy user management removed, subscriptions and credits live on Stripe.
  • New React frontend with a feature-based architecture that the team keeps extending.
  • Billing and credit model documented with diagrams so product and engineering share one picture.
  • Python (FastAPI)
  • PostgreSQL
  • SuperTokens
  • Stripe
  • React
  • TypeScript
  • Vite
  • Tailwind
  • Docker
  • AWS

Experience

Projects and positions

Freelance projects and permanent positions at software companies, consultancies and enterprises. From ERP systems for SMEs to an enterprise GenAI platform and a multi-tenant digital twin platform.

  1. 08/2025 to todayPermanent

    Lead Developer

    Nuvus · Virtual hardware and digital twins for automotive and space

    • Architecture decisions, team leadership and technical mentoring in a startup engineering team
    • External architect and lead engineer in client projects delivered through Nuvus, see Bosch and WeDaVinci below
    • Selection, vetting and placement of developers and freelancers for client projects
    • Python
    • TypeScript
    • React
    • Azure
    • Terraform
    • Docker
  2. 01/2026 to 10/2026via Nuvus

    Software Architect and Lead Engineer

    Bosch · Industrial engineering, digital twin platform

    • Set up the monorepo for a multi-tenant digital twin platform and owned architecture, infrastructure and core backend components as the most active contributor
    • Tenancy for SaaS and bring-your-own-cloud from one codebase, identity on self-hosted Zitadel with OIDC and automated tenant onboarding
    • Terraform on Azure Container Apps, Service Bus, IoT Hub and Key Vault, private network with a single public proxy, migration from Cosmos DB to MongoDB Atlas
    • Dedicated ingest service with certificate-based MQTT ingress, Prefect 3 workflow engine, security hardening, Angular to React migration, shared CI/CD templates
    • Python
    • FastAPI
    • React
    • TypeScript
    • MongoDB Atlas
    • Azure
    • Terraform
    • Zitadel
    • MQTT
    • Prefect
  3. 08/2025 to 05/2026via Nuvus

    Senior Full-Stack Developer

    WeDaVinci GmbH · AI video platform

    • Designed and built the user management service (FastAPI, PostgreSQL) as central hub for authentication, subscriptions, credits and billing
    • SuperTokens authentication with Google sign-in and session cookies shared across subdomains, legacy user management replaced
    • Stripe subscriptions and a credit model with reservation and refund for long-running video generation
    • React storyboard and video editor with trimming, versioned variants, image-to-video and PDF/ZIP export; frontend rebuilt from Angular to React
    • Python (FastAPI)
    • PostgreSQL
    • SuperTokens
    • Stripe
    • React
    • TypeScript
    • Tailwind
    • Docker
    • AWS
  4. 04/2025 to 07/2025Freelance

    Senior Full-Stack Developer

    Quantrefy GmbH · ESG data analytics

    • Middleware for connecting and aggregating five external ESG data provider APIs with PHP (Laravel)
    • Integration into the Quantrefy platform for analysis, reporting and forecasting of ESG data
    • Test automation with Pest and unittest including GitHub Actions
    • PHP (Laravel, Symfony)
    • Python (FastAPI, Pandas)
    • Node.js
    • AngularJS
    • TypeScript
    • Docker
  5. 09/2024 to 03/2025Permanent

    Backend Developer

    dmTECH GmbH · Retail, GenAI platform

    • Co-developed the enterprise GenAI platform dmGPT with FastAPI, Chainlit and React
    • APIs for document management, integration of external sources such as SharePoint and connection of Claude for internal process optimisation
    • Specialised AI assistants, among them an incident management assistant, plus support of all departments working with dmGPT
    • Python
    • React
    • TypeScript
    • PostgreSQL
    • pgvector, Qdrant
    • Kubernetes
    • Azure
  6. 11/2022 to 05/2024Permanent

    Technical Implementation Engineer

    Cobrainer GmbH · HR tech, talent platform

    • Integrated four enterprise customer systems into the Cobrainer talent platform
    • Migration and integration APIs plus a web-based service management tool for monitoring running integration projects
    • OpenAI API integration for automated job descriptions and personalised sales demos
    • Python (Django, FastAPI)
    • Kotlin
    • React
    • TypeScript
    • Azure
    • AWS
  7. 04/2021 to 10/2022Permanent

    IT Consultant

    BCM Solutions GmbH · IT consulting

    • New sales platform with PHP and Vue.js and redesign of existing sales software
    • Technical lead of an internal department for system integrations and interface architectures
    • Integration of customer systems via API connections and middleware services
    • Python
    • PHP
    • Vue.js
    • Node.js
    • React
    • Kubernetes
  8. 02/2019 to 11/2020Permanent

    Full Stack Developer

    Sternad Software GmbH · Software for small and medium businesses

    • Independently built a custom ERP system for three SME customers including replacement of their legacy systems
    • Customer consulting on process digitalisation and data migration
    • Modernised a legacy crisis management system with new API integrations
    • Python (Django)
    • PHP (Symfony)
    • Vue.js
    • Docker
    • PostgreSQL
  9. 06/2017 to 01/2019Permanent

    Full Stack Developer (apprenticeship)

    heureka e-Business GmbH · E-business agency

    • Rebuilt the company website and developed internal tools for time tracking and project evaluation
    • Introduced Docker and migrated from SVN to Git including workshops for colleagues
    • ColdFusion
    • React
    • JavaScript
    • Docker
    • PostgreSQL

Technologies

My stack

Tools I use in production. I pick up new technologies quickly when a project calls for it.

Backend

  • Python (FastAPI, Django, Flask)
  • Node.js (Express, Fastify)
  • PHP (Laravel, Symfony)
  • Kotlin

Frontend

  • React (Redux)
  • TypeScript
  • Next.js
  • Tailwind CSS
  • Vue.js

Data and AI

  • PostgreSQL, pgvector
  • MongoDB Atlas
  • Qdrant
  • Pandas, NumPy, spaCy
  • LLM integration (Claude, OpenAI)

Cloud and DevOps

  • Microsoft Azure, AWS
  • Terraform
  • Docker, Kubernetes, Helm
  • GitHub Actions, GitLab CI
  • MQTT, Prefect

How we work together

From first call to handover

Four steps, no surprises. You see working software early and your team can take over at the end.

  1. 01

    Intro call

    Thirty minutes on your problem, your team and your constraints. You get an honest answer on whether I am the right fit, and if not, who might be.

  2. 02

    Scope and offer

    A written scope with approach, risks and an estimate. Direct contract or through an intermediary, whichever you already have in place.

  3. 03

    Delivery in iterations

    Working software early and regularly, reviews with your team, tests and CI/CD from the first week. No big-bang handover at the end.

  4. 04

    Handover

    Documentation, decision records and knowledge transfer so your team runs and extends the result without me. Ongoing support if you want it.

About

Who you are working with

Portrait of Christian Worsch

I am a software architect and senior developer from Wurmberg near Stuttgart. I started building software professionally in 2017 and have since worked in an agency, in software companies, in consulting and in an enterprise GenAI team, as developer, consultant and lead engineer. Since 2025 I take on client projects as a freelancer and, since August 2025, as Lead Developer at Nuvus, a startup that turns real hardware into executable digital twins for automotive and space. Through Nuvus I was most recently external architect and lead engineer for a multi-tenant digital twin platform for industrial plants on Azure. Client projects can be contracted through Nuvus or directly with me, whichever fits your procurement.

What has not changed in all those roles: I prefer simple, sustainable solutions to short-term workarounds, I design architectures that the team can understand and extend without me, and I stay in the code instead of handing over slide decks. Tests, CI/CD and documentation are part of the delivery, not an afterthought.

Certificate

  • IHK certified IT Project Coordinator2019

FAQ

Practical questions

Remote or on site?
Remote by default. Occasional on-site days for kick-offs, workshops or reviews are fine. If your office is near Stuttgart, Karlsruhe or Pforzheim, regular on-site work is possible.
Who is the contracting party?
Your choice. Directly with me as a freelancer, through my employer Nuvus, or through a recruiter or agency you already work with. The person doing the work is the same in every case.
Is there a minimum project length?
No. From a few days of architecture review or consulting to engagements over many months. Capacity is agreed per project, up to full-time.
What does it cost?
Daily or hourly rate depending on scope and duration. Ask for a quote in the intro call.
Which languages do you work in?
German (native) and English (business fluent). Documentation and code in English unless your team prefers otherwise.
What do you not do?
Pure design or marketing work, and projects where I would only be a pair of hands without influence on the technical approach.

Contact

Let us talk about your project

Send me a short note on what you need: the task, the timeframe and the technologies involved. I will get back to you promptly with an honest assessment of whether and how I can help.