• Independent backend and full-stack engineering consultancy. Selected client engagements below (reverse chronological).

E-commerce integration platform unifying SAP S/4HANA Cloud (orders, fulfillment) and Salesforce (customer/CRM) into one data layer for Hilti Online storefronts and internal tooling across multiple country markets.

• Joined as senior QA engineer; promoted to senior developer within 3 months on the strength of test-infrastructure and non-functional contributions.
• Extended the Cucumber/WireMock suite with an assertion framework - verifying whether an endpoint was (or was not) invoked and whether specific headers, parameters, and body fields were present or absent plus proxy-control tooling to selectively mock outbound calls while passing others through to live systems, turning production incidents into reproducible regression tests.
• Authored a reusable test-support utility (TestCompletion) that lets engineers declare mock behavior and its verification together and runs all assertions at test completion cutting boilerplate and standardizing given/when/then tests across the team.
• As senior developer, owned functional and non-functional requirements alike - structured logging, cross-service trace IDs, aggregated logging, load testing, and security - the production-readiness layer that separates working code from software that survives in a live multi-market environment.

Backend engineering on the mobile-ticketing platform of Cubic the world's largest public-transport fare-collection operator (24B+ transactions a year) - serving operators across Germany, the EU, and the USA.

• Inherited a codebase carrying heavy technical debt and led a ground-up refactor of the entire security layer, replacing ad-hoc, duplicated logic with a consistent model.
• Extracted shared libraries reused across all services to eliminate duplication, and used the consolidation to retire use cases that were no longer needed - trimming a significant number of classes from the platform.

Serverless backend for Vodafone's device trade-in service (trade an old handset for credit toward a new one) across five European markets.

• Designed and delivered event-driven serverless services on AWS Lambda (Node.js/TypeScript), and established reference patterns for well-structured serverless code clean separation, testability, Serverless Framework - demonstrated to the wider team through PoCs.
• Built and maintained CI/CD pipelines in GitHub Actions covering automated testing and multi-environment deployment; provisioned infrastructure as code with Terraform.

Led the backend migration of Porsche's customer identity platform from a Keycloak + Java + relational-DB stack to Auth0.

• Migrated authentication flows and user data to Auth0 with minimal service disruption; rebuilt the integration layer in Node.js/TypeScript.

Owned a key component of Vodafone's consumer-IoT/smart-home platform-an IFTTT-style proposition that grew from an incubation PoC into its own product, live in 7 markets at peak.

• Designed and led implementation of the platform's "provisioning backend" a resilient state machine orchestrating all customer flows (device enrollment, payment, SIM activation, subscription renewal), built for fault tolerance and safe recovery from partial failures.
• Created a JSON-based DSL ("recipes") that let teams declaratively define provisioning flows flow-control steps, payment handling, retries - interpreted and executed by the state machine.
• Defined an extensibility framework so external device manufacturers could add their own steps and onboard a new device reusing platform steps for payment and SIM activation while calling their own backend without touching core code.
• Established the team's engineering standards end to end: Git Flow with feature branches, strict code review, squash-merge to develop, and platform-wide naming, package-structure, and responsibility conventions refactoring the codebase for consistency.

Backend engineer across xarvio, a world-leading digital-farming platform (100,000+ farmers, 15M+ hectares, 100+ countries) built on 100+ Java microservices over RabbitMQ.

• Worked across the full platform rather than a single service silo, building services that ingested nightly weather data and in-field sensor/machine telemetry to compute agronomic metrics over hundreds of thousands of hectares worldwide.
• Contributed to agronomic data-processing services at scale within a large event-driven architecture, with contract-tested Feign clients and WireMock-based integration tests safeguarding cross-service reliability.
• Used Testcontainers to spin up real RabbitMQ and PostgreSQL instances for integration tests, and Flyway for versioned database schema migrations across services.

Led a rapid-prototyping team evaluating emerging technologies and improving existing Vodafone products; delivered a high volume of proofs-of-concept across a broad technology range.

• Built an end-to-end test-automation platform for a complex NFC/SIM mobile-wallet (mWallet) product, aggregating logs across multiple integrated systems and using rule-based expressions to pinpoint failures - cutting issue diagnosis from days to minutes.
• Delivered low-level Android work: recompiled the kernel to enable Token Bucket Filter (per-application bandwidth control by process ID) and built native contact-sync that eliminated merge errors on product switchover.

• Built a web-based visual content editor (Blueprint) for Vodafone 360 - a SmartGWT thick client over a Spring/Hibernate backend and, as team lead, owned task breakdown and delivery; also sustained the Vodafone Live! platform.