Michel Neumann

Senior Software Engineer

Banking Systems & Technical Delivery · Healthcare IT

About Me

With 10+ years of experience, I solve engineering challenges for businesses that need reliable payment systems, banking integrations, and scalable infrastructure. I work across the full delivery lifecycle: analysing business and operational requirements, designing technical solutions, implementation, testing, production rollout, and operational support.

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. My core stack covers TypeScript, JavaScript, Java, libraries such as React, Node.js, and Spring Boot on the application layer, and Kafka, AWS, Docker, Terraform, PostgreSQL, and Looker on the infrastructure, integration, and data side.

Work Experience

Senior Software Engineer

Nelly Solutions GmbH

Jul 2025 — Present

Berlin, Germany

Drove initiative to replace a legacy PDF generation system for invoice processing with a React-based solution, reducing render time and file size while improving developer experience through code-first templating
Participated in infrastructure and deployment modernisation efforts across multiple engineering teams
- ›Implemented and tested code changes to migrate customer notifications from Sendgrid to AWS SES for compliance reasons
- ›Migrated owned production services from shared EC2 to ECS containers, identifying candidates, testing deployments, and executing phased rollouts for zero-downtime transitions
- ›Prepared owned services for Continuous Deployment adoption, improving test coverage, enforcing pre-merge quality gates and briefing engineers on deployment processes
Contributed to cross-functional financial operations projects
- ›Migrated invoice processing to a new factoring provider, involving thousands of invoices with minimal service disruption
- ›Implemented and tested invoice-to-treatment-plan matching logic, added observability, and collaborated with product and operational stakeholders on follow-up changes
Participated in the production on-call rotation, diagnosing distributed-system incidents, resolving customer and stakeholder escalations, and coordinating remediation and preventative improvements

[TypeScript][React][Node.js][Kafka][AWS][Docker][PostgreSQL][Looker][Terraform][GitHub Actions][LaunchDarkly]

Senior Software Engineer

Klarna Bank AB

Promoted from Software Engineer · 2024

Jan 2022 — Jun 2025

Berlin, Germany

Built Java-based backend systems enabling Klarna's connectivity to banking networks (SEPA, SWIFT), with idempotent API design and concurrency-safe transaction handling processing €1M+ daily 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, generating ~20M SEK since launch
Developed customer-facing features for the Klarna App: card activation, credit card management, and native wallet integrations (Apple Pay, Google Pay) serving millions of users
- ›Led technical investigations supporting compliance requirements for US military service members
- ›Delivered system supporting the Klarna Card product proposition in GB markets
- ›Contributed to redesign of 'Card Home' and activation flows, reducing errands and increasing engagement
Built Klarna Card functionality for the internal customer service platform, supporting ~400 active agents daily with statements, forbearance, deferrals and transaction history tooling
Served as 'Readiness Lead' coordinating 20+ teams for load testing, operational readiness, and compliance, resulting in zero incidents in the Card & Banking domain during Black Friday peak traffic
Participated in the production on-call rotation for banking and card services, resolving incidents and customer escalations through root-cause analysis and coordinated remediation

[Java][Spring Boot][AWS][React Native][PostgreSQL][Datadog][Jenkins]

Founding Engineer

Spreewunder

Jul 2018 — Dec 2021

Berlin, Germany

Tech-led development of an on-premise video surveillance platform for retail, architecting backend systems to connect to ONVIF-based surveillance cameras, including client consultation and full-stack implementation in Python and Angular
- ›Delivered a system capable of displaying up to 64 camera feeds in a browser in real-time using DASH/HLS streaming, running 24/7 in an intranet environment with motion-triggered and AI-powered theft detection
Designed and implemented peer-to-peer infrastructure for the 'Secuvid' video conferencing SDK using WebRTC, with end-to-end encryption, licensed to a German healthcare patient management provider
- ›Created API interfaces for SDK components and enabled package-based distribution
Built a real-time cardiovascular data analysis app integrating Bluetooth 12-lead ECGs, designing, implementing and training AI models for heart data classification and developing a web-based interface for clinical use

[Python][Keras][TensorFlow][Angular][JavaScript][WebRTC][REST APIs][Docker]

Software Engineer

Fraunhofer FOKUS

May 2016 — Jun 2018

Berlin, Germany

Contributed to the 'Cloudless' framework, implementing a 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.js][JavaScript][WebRTC][IoT]

Web Development Intern

Wazoku

Oct 2014 — Mar 2015

London, United Kingdom

Contributed to the 'Idea Spotlight' innovation management platform using AngularJS and Python
Rebuilt and relaunched the company website using WordPress and PHP, collaborating with design and marketing teams

[AngularJS][Python][WordPress][PHP]

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Education

M.Sc. International Media & Computing

HTW Berlin

2012 — 2018 · Berlin, Germany

Master thesis: 'Application of artificial neural networks in web browsers using ECG data' (grade 1.5)

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Certifications

AWS Solutions Architect Associate

SAA-C03

AWS Certification · November 2023

Acquired the AWS Solutions Architect SAA-C03 certification to enhance my skill set and advance my career in cloud computing.

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Languages

GermanNative
EnglishFluent