Patrick Seelemeyer - Senior Software Engineer

Q: Where is Patrick based?

Patrick is based in Halle (Saale), Germany .

Q: What languages does Patrick speak?

Patrick speaks the following languages: English (Advanced), Chinese (Advanced) .

Q: How many years of experience does Patrick have?

Patrick has at least 11 years of experience. During this time, Patrick has worked in at least 4 different roles and for 4 different companies . The average length of individual experience is 3 years and 10 months . Note that Patrick may not have shared all experience and actually has more experience.

Q: What is Patrick's latest experience?

Patrick's most recent position is Senior Software Engineer at Delivery Hero .

Q: What companies has Patrick worked for in recent years?

In recent years, Patrick has worked for Delivery Hero and Spotify .

Q: Which industries is Patrick most experienced in?

Patrick is most experienced in industries like Healthcare , Tourism and Hospitality , Media, and Entertainment and Publishing . Patrick also has some experience in Retail , Banking and Finance , and Information Technology (IT) .

Q: Which business areas is Patrick most experienced in?

Patrick is most experienced in business areas like Information Technology (IT) , Product Development , and Finance .

Q: Which industries has Patrick worked in recently?

Patrick has recently worked in industries like Healthcare , Tourism and Hospitality , Media, and Entertainment and Publishing .

Q: Which business areas has Patrick worked in recently?

Patrick has recently worked in business areas like Information Technology (IT) , Product Development , and Finance .

Recommended expert

Halle (Saale), Germany

Experience

May 2021 - Sep 2025

4 years 5 months

Berlin, Germany

Senior Software Engineer

Delivery Hero

Led a team of 6 software engineers to develop and maintain an AI-driven healthcare platform, enabling automated diagnostics and prescriptions based on real-time ECG data analysis
Designed and developed a robust Revenue Cycle Management (RCM) system, integrating HL7 and FHIR APIs to enable seamless interoperability, real-time data exchange, and HIPAA-compliant data handling, improving billing efficiency, claim processing, and regulatory adherence in healthcare operations
Migrated a legacy monolithic application to a scalable microservices architecture, enhancing system modularity, scalability and maintainability while implementing key design patterns such as Strangler, Database-per-Service, API Gateway, Saga and CQRS for efficient service communication and transaction management
Architected and led a C# 9/.NET 6 microservices ecosystem handling hotel reservations, payments, and loyalty programs, enabling 99.99% uptime across 10+ services
Defined OpenAPI/Swagger contracts and auto-generated client SDKs, reducing front-to-backend integration time by 50%
Containerized each service with Docker and orchestrated deployments via Kubernetes, slashing release lead time from days to hours
Designed PostgreSQL schemas optimized for high-volume transactional workloads and implemented Redis caching layers to accelerate read-heavy endpoints by 80%
Built Kafka streaming pipelines for real-time availability updates and audit logs, processing 2 million+ events per hour with end-to-end delivery guarantees
Implemented unit and integration tests for React applications using Jest and React Testing Library, ensuring 80%+ test coverage, improving component reliability, and preventing regressions
Defined and deployed AWS cloud infrastructure using Terraform, while containerizing and orchestrating microservices with Docker and Kubernetes, improving automation and system scalability
Built a scalable full-stack booking application using React 18 and Django REST Framework, integrating Celery and Redis for asynchronous task processing, while deploying on GCP with Cloud Run and Firestore, enabling real-time scheduling, payment processing, and automated notifications
Mentored junior developers through code reviews, pair programming, and knowledge-sharing sessions, improving team efficiency by 30% while maintaining comprehensive API documentation using Swagger/OpenAPI

Aug 2018 - Apr 2021

2 years 9 months

Berlin, Germany

Senior Web Developer

Spotify

Architected high-throughput microservices in Java and Scala on Google Kubernetes Engine, leveraging Spring Boot and Akka HTTP to serve over 50 million playlist requests per day with 99.9% uptime
Built real-time event pipelines with Apache Kafka and Scio (Apache Beam/Dataflow), processing 1.2 billion user interactions daily to power personalized Discover Weekly and Release Radar playlists
Optimized metadata storage by tuning Apache Cassandra clusters—implemented advanced compaction and schema strategies that reduced 99th-percentile read latency from 120 ms to 45 ms and cut storage costs by 25%
Developed domain-driven .NET Core microservices for room-rate calculation and channel management, applying CQRS and event sourcing patterns for clear separation of concerns
Leveraged Docker Compose for local development and Azure Container Registry for production images, standardizing environments across teams
Implemented PostgreSQL partitioning and advanced indexing strategies, achieving sub-20 ms response times on 500 million+ row tables
Integrated Redis Streams to buffer burst traffic and smooth cache invalidation, reducing origin DB load by 70%
Consumed and produced to Kafka topics for cross-service messaging, ensuring reliable event delivery and simplifying inter-team contracts
Designed and deployed scalable serverless architectures for SaaS-based B2B and B2C applications using AWS Lambda, API Gateway, AWS AppSync, and DynamoDB, integrating AWS IAM for secure access control, while ensuring high availability, cost efficiency, and seamless auto-scaling
Designed and managed scalable infrastructure with AWS CDK and CloudFormation, streamlining deployments faster and more reliable across different environments
Optimized performance and cost by reducing cold start latency, using SQS & SNS for asynchronous processing, and implementing caching strategies with DynamoDB Accelerator (DAX) and Redis
Demonstrated strong problem-solving, communication, and collaboration skills, effectively working with cross-functional teams to deliver scalable solutions, streamline workflows, and drive project success in fast-paced environments

Jul 2016 - Jul 2018

2 years 1 month

Berlin, Germany

Frontend Engineer

Zalando

Developed a full-stack iGaming platform, integrating cryptocurrency payments (Bitcoin, Ethereum) via Web3 APIs, ensuring smooth transaction management, secure wallet operations, real-time gameplay features, and a scalable backend for enhanced user engagement and efficiency
Managed Firestore and Firebase Authentication on GCP, optimizing database performance, securing user authentication, and ensuring seamless integration with cloud services for scalable and reliable applications
Designed and led development of 12 domain-oriented C# 9/.NET 6 microservices (reservations, billing, loyalty) using CQRS via MediatR and event sourcing with Kafka
Conducted design sessions and code reviews in Mandarin with the China engineering squad, eliminating hand-off delays and boosting feature delivery by 35%
Employed Swashbuckle v6 to auto-generate OpenAPI 3.0 specs and Swagger UI, slashing frontend integration time by 50%
Packaged each service in Docker 20.10 containers and managed deployments on AKS (Kubernetes 1.25), cutting release cycles from days to hours
Modeled PostgreSQL 14 schemas with table partitioning and pgBouncer pooling; integrated Redis 6.2 as a distributed cache to reduce read latency by 80%
Configured and optimized Cloudflare and Nginx for secure, high-performance web applications, implementing CDN caching, DDoS protection, load balancing, and reverse proxy setups to enhance speed, security, and scalability
Collaborated with DevOps engineers to optimize and support CI/CD pipelines using GitHub Actions and Jenkins, streamlining automation and deployment processes for enhanced efficiency and reliability

Jun 2014 - Jun 2016

2 years 1 month

Software Consultant (Full Stack)

ThoughtWorks

Developed enterprise web applications using Ruby on Rails and React
Delivered agile consulting for fintech and healthcare clients
Developed backend functionality with Python and Java, optimizing data processing efficiency by 25% by applying OOP, SOLID principles, data structures, and algorithmic optimizations to improve performance
Gained hands-on experience with AWS and GCP, utilizing services like EC2, S3, Lambda, Cloud Functions, BigQuery, and Firestore to deploy, manage, and optimize cloud-based applications for scalability and performance

Industries Experience

See where this freelancer has spent most of their professional time. Longer bars indicate deeper hands-on experience, while shorter ones reflect targeted or project-based work.

Experienced in Healthcare (6.5 years), Tourism (4.5 years), Media and Entertainment (2.5 years), Retail (2 years), Banking and Finance (2 years), and Information Technology (2 years).

Healthcare

Tourism

Media and Entertainment

Retail

Banking and Finance

Information Technology

Business Areas Experience

The graph below provides a cumulative view of the freelancer's experience across multiple business areas, calculated from completed and active engagements. It highlights the areas where the freelancer has most frequently contributed to planning, execution, and delivery of business outcomes.

Experienced in Information Technology (11.5 years), Product Development (9 years), and Finance (4.5 years).

Information Technology

Product Development

Finance

Summary

Bachelor-level educated, result-driven & solution-oriented software engineer who is passionate about solving complex problems.

Great remote team-player, who loves working at fast-paced, agile environment.

Skills

Programming Languages: Javascript (Es6+), Typescript, Node.js, Python, Html5, Css3, Xml, Json
Architecture & Apis: Microservices, Event-driven Architecture, Graphql, Rest Apis, Websocket Api, Webrtc
Backend Development: Nest.js, Express.js, Django (Drf), Fastapi, Rabbitmq, Apache Kafka, Grpc
Frontend Development: React, Redux, Next.js, React Native, Angular, Ngrx, Rxjs, Vue.js, Tailwindcss, D3.js, Three.js
Databases & Data Processing: Sql, Nosql, Postgresql, Mysql, Mongodb, Cassandra, Dynamodb, Clickhouse, Redis
Cloud & Devops: Aws, Gcp, Azure, Heroku, Docker, Kubernetes, Jenkins, Github Actions, Gitlab Ci, Circleci
Testing & Tools: Jest, Mocha, Chai, Pytest, React Testing Library, Cypress, Sentry, Datadog, Grafana, Celery
Agile & Project Management: Scrum, Kanban, Jira, Slack, Microsoft Teams, Trello, Asana, Notion
Soft Skills: Leadership, Cross-functional Team Collaboration, Communication, Problem-solving, Flexibility, Time-management

Languages

English

Advanced

Chinese

Advanced

Education

Aug 2012 - May 2016

National University of Singapore (NUS)

Bachelor of Computing in Computer Science · Computing in Computer Science · Singapore

Profile

Created

November 2025

Need a freelancer? Find your match in seconds.

Try FRATCH GPT

Frequently asked questions

Do you have questions? Here you can find further information.

Where is Patrick based?

Patrick is based in Halle (Saale), Germany.

What languages does Patrick speak?

Patrick speaks the following languages: English (Advanced), Chinese (Advanced).

How many years of experience does Patrick have?

Patrick has at least 11 years of experience. During this time, Patrick has worked in at least 4 different roles and for 4 different companies. The average length of individual experience is 3 years and 10 months. Note that Patrick may not have shared all experience and actually has more experience.

What roles would Patrick be best suited for?

Based on recent experience, Patrick would be well-suited for roles such as: Senior Software Engineer, Senior Web Developer, Frontend Engineer.

What is Patrick's latest experience?

Patrick's most recent position is Senior Software Engineer at Delivery Hero.

What companies has Patrick worked for in recent years?

In recent years, Patrick has worked for Delivery Hero and Spotify.

Which industries is Patrick most experienced in?

Patrick is most experienced in industries like Healthcare, Tourism and Hospitality, Media, and Entertainment and Publishing. Patrick also has some experience in Retail, Banking and Finance, and Information Technology (IT).

Which business areas is Patrick most experienced in?

Patrick is most experienced in business areas like Information Technology (IT), Product Development, and Finance.

Which industries has Patrick worked in recently?

Patrick has recently worked in industries like Healthcare, Tourism and Hospitality, Media, and Entertainment and Publishing.

Which business areas has Patrick worked in recently?

Patrick has recently worked in business areas like Information Technology (IT), Product Development, and Finance.

What is Patrick's education?

Patrick holds a Bachelor in Computing in Computer Science from National University of Singapore (NUS).

What is the availability of Patrick?

Patrick is immediately available full-time for suitable projects.

What is the rate of Patrick?

Patrick's rate depends on the specific project requirements. Please use the Meet button on the profile to schedule a meeting and discuss the details.