Jest Experts in Munich

Project: Tax Exemption Order Application

The client has an existing application for creating and maintaining tax exemption orders for end customers; design and implementation of a comparable application for internal employees.

• Design and implementation of microservices and the UI for the business area "tax exemption orders" using Domain Driven Design as well as Spring Boot and Angular.
• Implementation of reactive, non-reactive, and asynchronous APIs (Spring REST, WebFlux, GraphQL).
• Development of the Angular application, including state management using Signals, RxJS Observables, and subscriptions.
• Securing the API and the application using OAuth2, JWT, and OpenID Connect.
• Configuration and setup of CI/CD pipelines with Jenkins.
• Collaboration with cross-functional teams and conducting code reviews.

Environment: Java, Spring Boot, Angular 18 & 19 (standalone, signals), RxJs, Bootstrap CSS, Vitesting, OpenShift, Istio, microservices, Kafka, Dynatrace, Jenkins, GitLab, Graylog, Sonar, Oauth2, OracleDB

• Delivered backend systems, data processing solutions, and software integrations for enterprise business applications.
• Designed and implemented API-based services connecting internal platforms with external systems.
• Built automated processing workflows to handle large-scale structured business data.
• Improved application performance by 30–50% through database optimization, caching strategies, and backend refactoring.
• Reduced manual operational effort by 40–60% by automating repetitive workflows.
• Supported production environments through troubleshooting, monitoring improvements, and continuous optimization.
• Authored technical documentation and led knowledge-transfer sessions to support long-term maintainability.

• Technologies: TypeScript, JavaScript, Java, HTML, SCSS, JSON, REST, Angular, Nx, NgRx, RxJs, Git, Spring, TFS, Jenkins, Jest, Cypress, UI/UX-Design, Figma, Storybook, Domain-Driven Design (DDD), Micro Frontend, Clean Code, Arc42, Agile, Scrum, Jira, Confluence
• Technical conception and further development of a modern Angular web application as part of the portal migration
• Built a modular frontend architecture with Nx and clear separation of domain and technical layers (Clean Architecture)
• Introduced and implemented Domain-Driven Design in the frontend context, including layer model and linting rules for code organization
• Developed reusable UI components and features using Angular, NgRx and RxJS
• Integrated the application with backend services via REST APIs
• Ensured high code quality through structured code reviews, testing with Jest and Cypress and introduction of guidelines
• Performed regular upgrades to new Angular versions to ensure long-term maintainability
• Collaborated closely with internal developers, product owners and stakeholders for requirements analysis and solution finding
• Supported the team through active knowledge transfer, review coaching and technical decision making
• Established a modular architecture with Nx & DDD as the technical foundation for future development
• Significantly improved test coverage through systematic introduction of Cypress and Jest tests
• Facilitated intensive collaboration with internal developers to build DDD structures and testing strategies
• Delivered a modernized UI focusing on clarity, usability and modern web technologies, achieving high acceptance by over 4,000 field staff
• Enabled parallel operation of the new Angular portal with the existing .NET system for phased migration of the sales process

• Development of an accessible, responsive website based on Figma designs for a major sports event in compliance with WCAG, BITV, and EN 301 549
• Technical planning and setup of the tool stack with Vite, Playwright, Docker, and GitLab CI
• Worked on two existing projects (Vue.js & Nuxt), with a focus on bug fixing, accessibility audits, and new feature development
• Collaboration with design and QA to consistently implement accessible UI patterns
• Consulting on improving existing frontend architectures with regard to accessibility, performance, and maintainability

• Designed and developed a high-performance internal resource management platform using React and TypeScript, optimizing dynamic data rendering and state management.
• Built a React Native application to support mobile access to internal tools, enabling on-the-go project tracking for field teams.
• Developed custom 2D canvas-based visualizations using Pixi.js to simulate material flows and refractory layer behaviors.
• Integrated Pixi.js with React components for interactive diagrams and real-time UI updates.
• Developed interactive 3D visualizations using React.js for displaying refractory product layouts and simulations, supporting engineering and sales teams with dynamic product previews.
• Integrated Three.js within the React ecosystem to allow manipulation of 3D models in real-time via browser, enhancing user engagement and field configurability.
• Integrated a headless CMS to enable dynamic content updates by non-technical users, reducing content deployment time by 40%.
• Led AWS CloudFront optimization initiatives, improving portal load speeds by 30% globally.
• Actively collaborated with cross-functional Agile teams and product owners to deliver prioritized features with a fast feedback loop.
• Key Technologies: React.js, React Native, Three.js, TypeScript, Contentful CMS, AWS S3/Lambda/CloudFront, Cypress, Agile Scrum

• Development of a test system
• Establishment of the architecture using Scala/Java for the backend and Swing for the frontend
• Setup of CI/CD pipelines with Jenkins for continuous integration, including automated builds
• Participation in the Scrum team, including daily stand-ups, sprint planning, and retrospectives
• Technology environment: Scala, Swing, EJB, JPA, Scrum, PostgreSQL, Mercurial

• Designed and developed the "Credit Risk Engine" using Camunda, Node.js and Typescript
• Greenfield project for credit card credit assessment for existing and new customers, including EBA KPIs, SCHUFA and CRIF scorings
• Built and modeled workflows (BPMN) and decision logic (DMN) with Camunda Modeler in close collaboration with stakeholders
• Implemented service tasks, user tasks and jobs with Nest.js, Node.js and Typescript, including exception handling
• Backend-for-Frontend (BFF), frontend with React, Tailwind and Ant Design UI library
• CI/CD with GitLab, Kubernetes/Rancher

I have worked across multiple international client projects, holding senior roles including Software Architect, Senior Software Developer, Technical Lead, and Lead Backend & DevOps Engineer. My experience spans complex enterprise environments in banking, financial services, telecommunications, engineering, and automotive domains, supporting organisations such as UniCredit Bank, Telefónica O2, and BMW.

At UniCredit Bank, within the Securities Domain Transformation program, I led the modernisation of legacy monolithic systems into cloud-native Spring Boot microservices and an Angular frontend deployed on Google Cloud Platform. Beyond implementation, I was responsible for defining the target architecture, producing system architecture diagrams and sequence diagrams, and preparing API contract documentation for clients. I designed RESTful APIs and integrated Apigee for secure and reusable cross-project service consumption of APIs. I architected Kubernetes-based deployments using Helm. CI/CD pipelines were built with Jenkins, automating code analysis using Sonar, as well as testing and deployment stages. Defining clean coding principles for the project, conducting regular code reviews, and mentoring junior developers were also among my tasks at UniCredit.

At Telefónica O2, I led the transformation of a legacy call centre desktop application into a cloud-native microservices and micro-frontend solution. I actively contributed to the platform architecture, creating system architecture diagrams, component diagrams, architecture documentation, and ADRs for future references. I improved the performance and scalability of the services. I optimised AWS infrastructure costs, particularly by minimising the use of DynamoDB and reusing test environments effectively. Observability was implemented using Prometheus, Grafana, CloudWatch, and Splunk dashboards. CI/CD pipelines were delivered using GitLab, Docker, Kubernetes, and AWS. Conducted techinical sessions for teams.

• Built middleware service integrating EDI providers and marketplace partners with Microsoft Dynamics 365 to receive sales orders and communicate shipments, invoices, inventory, and price catalogues
• Utilized a mixture of REST APIs and event-driven data processing pipelines

• Migrated the Electric Vehicle Charging SaaS App of the EV Division from on-premises and Azure to AWS Cloud, resulting in a hybrid multi-cloud multi-tenant solution
• Developed a streaming data pipeline using AWS MSK for Apache Kafka and implemented an event-driven architecture to ingest and process near real-time data from OCPI-protocol IoT devices
• Implemented multi-tenant strategies including database schema isolation, bridge model for resource sharing, and tenant-based RBAC controls
• Provisioned Kubernetes clusters on AWS EKS with namespaces and RBAC for tenant isolation
• Led migration from on-premises and Azure to AWS using AWS DataSync, Snowball, and Database Migration Service
• Orchestrated collaboration across 5+ systems, vendors, service providers, and on-site teams
• Supported development and maintenance of IT strategy aligned with business requirements
• Managed €40 million infrastructure budget with AWS & Azure cost optimization, achieving 15% savings
• Led 50+ developers to implement advanced database procedures, increasing productivity by 20%
• Spearheaded multi-cloud, multi-tenant infrastructure migration for 30% faster processing times
• Negotiated vendor pricing to reduce payroll/benefits administration costs by 20%
• Developed a two-year infrastructure technology roadmap yielding 25% cost savings
• Tech stack: Kubernetes on AWS EKS, Docker, Kafka/AWS MSK, Terraform, AWS CDK, TypeScript, React, NextJS, Node.js, NestJS, Python, Aurora Serverless, RDS (MySQL, SQL Server), GitHub Actions, Azure DevOps, ArgoCD, AWS Lambda, API Gateway, AWS Security Hub, AWS Database Migration Service, AWS DataSync, AWS Organizations, AWS Control Tower, Odoo, Microsoft Navision, MS Dynamics

• Successfully migrated over 150 BI dashboards (Jira, Microstrategy, AWS QuickSight) as project lead of 4 developers, ensuring a smooth transition and maintaining data integrity.

• The software supports the complete planning and approval of antennas for mobile telephony.

• The system was implemented using an event-driven microservice architecture for cloud-native deployment with Quarkus on the backend, Kafka for communication, and Angular for the frontend. Services run on Kubernetes in Google Cloud. A special challenge was synchronizing with the legacy system still used by some users.

• Led an initiative to develop an IDE extension (VSCode). Created a vision and strategy, gathered and clarified requirements, coded a PoC and performed internal testing.
• Responsible for the architectural decisions and tradeoffs.
• Coached and organised knowledge sharing sessions with other engineers.
• Tech stack: ReactJS, NodeJS, AWS, Docker, TypeScript, Jest, Vitest, VSCode API, git.

• Evaluation of RAG for legal advisory (build or buy)
• Evaluation and POC of RAG for an ERP time tracking module
• Consulting on foundation model selection
• Setup AI development environment (eliminating shadow AI)
• AI strategy consulting
• AI-assisted code creation and context engineering make change sets larger
• Strong software engineering expertise, code reviews and safeguarding through pipelines and domain-specific automated test cases