Michel Neumann
Senior Fullstack Engineer
Payment & Banking Systems · Healthcare IT
10+ years of experience
Open to opportunitiesI solve engineering challenges for businesses that need reliable payment systems, banking integrations, and scalable infrastructure. My work spans financial services and healthcare IT, building systems that connect to banking networks, automate complex financial workflows, process high-volume transactions, and maintain regulatory compliance.
Work Experience
Senior Software Engineer
Nelly Solutions GmbH
- Architected and implemented a React-based PDF generation system for invoice processing, reducing render time and file size while improving developer experience through code-first templating
- Led migration of production services from shared EC2 infrastructure to ECS containers, identifying migration candidates, testing deployments, and executing phased rollouts to ensure zero-downtime transitions for a multi-bank factoring platform processing €10M+ monthly across 200+ healthcare practices
- Contributed to migration of invoice processing between factoring providers, implementing backend changes to support the new provider integration with minimal service disruption
- Built and enhanced internal tooling for factoring operations, streamlining invoice generation, partner bank reporting, and reconciliation workflows
TypeScriptReactNode.jsAWSECSDockerPostgreSQLTerraform
Senior Software Engineer
Klarna Bank AB
- Built Java-based backend systems enabling Klarna's connectivity to banking networks (SEPA, SWIFT), processing €1M+ daily in customer and internal transfers while ensuring PSD2 and GDPR compliance
- Tech-led automation of monthly fee processing using AWS Step Functions, reducing operational overhead by 12.5% for a serverless system serving hundreds of thousands of Klarna Card users across US and UK markets, generating approximately 20M SEK since launch
- Developed customer-facing features for Klarna App, including card activation flows, credit card management interfaces, and native wallet integrations (Apple Pay, Google Pay) serving millions of users
- Led technical investigations and communication to support compliance requirements for US military service members
- Led development and delivered system supporting Klarna Card product proposition in GB markets
- Contributed to redesign of "Card Home" and Klarna Card activation flows, reducing errands and increasing customer engagement
- Developed Klarna Card functionality for internal customer service platform, enabling agents to assist customers with requests related to card statements, forbearance, deferrals, transaction history and more, averaging approximately 400 active unique users daily
- Served as "Readiness Lead" coordinating 20+ engineering teams to execute load testing and resolve compliance issues, resulting in zero incidents in Card & Banking domain during Black Friday season peak traffic
JavaSpring BootAWSReact NativePostgreSQLDatadogJenkins
Software Engineer
Spreewunder
- Tech-led development of on-premise video surveillance platform for retail sector, architecting backend systems to support 64-camera deployments with DASH/HLS streaming, client consultation, and full-stack implementation using Python and Angular
- Successfully delivered a system capable of displaying up to 64 camera feeds in a web browser in real-time running 24/7 in an intranet environment, capturing video segments triggered by motion detection and AI-powered analysis
- Designed and implemented peer-to-peer infrastructure for "Secuvid" video conferencing SDK using WebRTC, featuring end-to-end encryption and privacy-first architecture, licensed to a German healthcare patient management system provider
- Created API interfaces for SDK components and enabled package-based distribution according to industry standards
- Built real-time cardiovascular data analysis application integrating Bluetooth-enabled 12-lead ECGs, training AI models for heart data classification and developing web-based interface for clinical use
PythonAngularJavaScriptWebRTCRESTful APIsDocker
Software Engineer
Fraunhofer FOKUS
- Contributed to the development of the "Cloudless" framework, implementing WebRTC-based peer-to-peer data synchronization layer for backend-less, end-to-end encrypted applications
- Developed backend solutions and IoT prototypes using Node.js, supporting research projects in distributed systems and connected devices
Node.jsJavaScriptWebRTCIoT
Web Development Intern
Wazoku
- Contributed to development of "Idea Spotlight" innovation management platform using AngularJS and Python
- Rebuilt and relaunched company website using WordPress and PHP, collaborating with design and marketing teams
AngularJSPythonWordPressPHP