Caleb C.-Senior Python Backend Engineer
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Experience
Senior Python Backend Engineer
Simon-Kucher
Transmission system operator – network provisioning platform (team lead)
- Designed the saga orchestrator in Python that provisions network fabrics with rollback.
- Split IP, identity, and resource allocation into bounded contexts with their own databases and typed clients.
- Implemented data access using DDD repositories and units of work, with no SQL in the domain code.
- Required integration tests using real PostgreSQL and RabbitMQ containers, and API fuzzing for every service.
- Introduced an agent workflow where a spec starts each change and a human approves every merge.
- Rolled out OpenTelemetry auto-instrumentation through GitOps across eighteen Kubernetes clusters.
- Led incident response for stuck provisioning and recorded every outage as a post-mortem.
Languages and software used: Python, FastAPI, Pydantic v2, SQLAlchemy async, PostgreSQL, RabbitMQ, Celery, pytest, testcontainers, schemathesis, Helm, Flux CD, GitLab CI, OpenTelemetry, pi coding agent.
Software product company – datacenter simulation SaaS (backend development)
- Built the asynchronous simulation pipeline as the second-largest contributor among more than twenty team members.
- Tagged every image by commit SHA and semver in the GitHub Actions deployment workflows.
- Diagnosed the RabbitMQ memory alarm that froze every simulation and fixed the limits in the Helm chart.
- Converted the test suite to function-style pytest, with coverage reported in every pipeline.
Languages and software used: Python, FastAPI, SQLAlchemy, Alembic, Celery, RabbitMQ, Redis, PostgreSQL, S3, EKS, Helm, Keycloak, GitHub Actions, pytest, mypy, ruff, SonarQube.
Internal AI platform – model serving and telemetry
- Built the FastAPI service that deploys open-weight models on GPU tiers as OpenAI-compatible endpoints.
- Upgraded production EKS by two Kubernetes minor versions and fixed zone-bound storage faults.
- Traced every model call, including its token count, cost, and latency, through the OpenTelemetry operator.
Languages and software used: Python, FastAPI, vLLM, LangGraph, pydantic-ai, OpenAI and Anthropic APIs, EKS, Helm, Flux CD, Terraform, GitLab CI, OpenTelemetry, Grafana.
Senior Software Engineer / ML Infrastructure
European Central Bank
- Built asynchronous microservices for the risk and regulatory modules with contract tests in CI.
- Automated container builds and AKS rollouts for these services with Azure DevOps.
- Managed production cluster operations and debugged failed deployments.
- Served RAG inference for regulatory questions using deterministic and semantic search with OpenSearch.
Languages and software used: Python, FastAPI, PostgreSQL, OpenSearch, RabbitMQ, LangGraph, Docker, Azure (AKS, ACR, Entra ID), Terraform, Azure DevOps, pytest, ELK.
Senior Python Backend Engineer – Turbine Fleet Platform
Siemens Energy
- Designed the in-house asyncio framework and ZeroMQ broker for every turbine service.
- Built the turbine performance service on a thermodynamic cycle program and its surrogate models.
- Led the migration of around thirty services from on-premises data centers to AWS.
- Packaged the platform for customer data centers as a Helm chart with single sign-on.
Languages and software used: Python, aiohttp, Quart, ZeroMQ, Kafka, RabbitMQ, PostgreSQL, DynamoDB, Redis, Keycloak, Docker, Kubernetes, Helm, Terraform, AWS, GitLab CI.
Deutsche Börse · HSBC Bank
Built trading, clearing, and payment systems at HSBC and Deutsche Börse, including SEPA and SWIFT.
Nomad Electronics
Industry experience
See where this freelancer has spent most of their professional time.
Experienced in Banking and Finance, Energy, Information Technology, and Utilities.
Business area experience
See which departments and functions this freelancer has contributed to most.
Experienced in Information Technology and Product Development.
Summary
Senior Python backend engineer across energy, banking, and consulting, building services and platforms on Kubernetes in AWS and Azure. At Simon-Kucher I lead the network provisioning team at a transmission system operator and run the internal AI platform's clusters. I implement each service with its own domain model and database, and release through GitOps to the clusters I run.
Skills
- Python & Backend: Python 3 (Asyncio, Strict Typing), Fastapi, Pydantic V2, Sqlalchemy Async, Alembic, Celery, Rest, Openapi, Rabbitmq, Postgresql, Redis, Opensearch
- Design & Testing: Domain-Driven Design, Bounded Contexts, Repository And Unit Of Work, Ports And Adapters, Saga, Pytest, Testcontainers, Schemathesis, Hypothesis
- Kubernetes & Cloud: Kubernetes (Eks, Aks), Helm, Flux Cd, Kustomize, Docker, Terraform, Aws (Eks, Ecr, Rds, S3, Lambda), Azure (Aks, Acr, Entra Id)
- Ci/Cd: Github Actions (Reusable Workflows, Self-Hosted Runners), Gitlab Ci, Azure Devops, Sonarqube, Semgrep, Bandit, Mypy, Ruff, Renovate
- Ai & Observability: Pi Coding Agent, Langgraph, Openai And Anthropic Apis, Opentelemetry, Prometheus, Grafana, Loki
Languages
Education
Middlesex University
Computer Science · London, United Kingdom
Certifications & licenses
Statistics
Experience
Global experience
Expertise
Qualifications
Frequently asked questions
Have questions? Find more information here.
Caleb is based in Berlin, Germany.
Caleb speaks the following languages: English (Advanced), Spanish (Advanced), Portuguese (Advanced), German (Intermediate).
Caleb has at least 17 years of experience. During this time, Caleb has worked in at least 3 different roles and for 5 different companies. The average length of individual experience is 3 years and 4 months. Note that Caleb may not have shared all experience and actually has more experience.
Based on recent experience, Caleb would be well-suited for roles such as: Senior Python Backend Engineer, Senior Software Engineer / ML Infrastructure, Senior Python Backend Engineer – Turbine Fleet Platform.
Caleb's most recent position is Senior Python Backend Engineer at Simon-Kucher.
In recent years, Caleb has worked for Simon-Kucher, European Central Bank, and Siemens Energy.
Caleb is most experienced in industries like Banking and Finance, Energy, and Information Technology. Caleb also has some experience in Utilities.
Caleb is most experienced in business areas like Information Technology and Product Development.
Caleb has recently worked in industries like Energy, Information Technology, and Utilities.
Caleb has recently worked in business areas like Information Technology and Product Development.
Caleb attended Middlesex University for Computer Science.
Caleb has 4 certificates. Among them, these include: AWS Solutions Architect, ISTQB, and ITIL.
Caleb will be available full-time from November 2026.
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The median daily rate is the middle value of all daily rates — half of comparable freelancers charge less, half charge more. Unlike the average, it is barely affected by outliers.
Calculated based on our freelancers’ daily rates as of 28 Oct 2026. Actual rates may vary depending on seniority level, experience, skill specialization, project complexity, and engagement length.
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