12/05/2025 updated

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Senior Full-Stack Developer | Problem Solver for Legacy → Scalable Systems | Node.js · Python · Next

Munich, Germany Bachelor of Science (BSc) Applied Computer Science with a Focus on Media Informatics
Munich, Germany Bachelor of Science (BSc) Applied Computer Science with a Focus on Media Informatics

Profile attachments

Resume Frank-Dieter Stadtler.pdf

Clean Code PrinciplesApplication Programming Interfaces (APIs)Amazon Web ServicesArchitectureAutomationCloud ComputingCode ReviewData ProcessingContinuous DeliveryContinuous IntegrationExtract Transform Load (ETL)Django Web FrameworkScalabilityPython (Programming Language)PostgreSQLMySQLNode.JsRedisSystems DesignTypeScriptWeb ApplicationsWorkflowsGoogle CloudReactJSDelivery PipelineBackendBackend ProgrammingFull Stack DevelopmentGraphqlNestJSRestful ApiDockerLegacy SystemsMicroservices
Senior Full Stack Developer with 10+ years of experience building scalable web applications and APIs using TypeScript, Node.js, and PostgreSQL. Proven track record in delivering production-grade systems for startups and enterprise clients alike. Skilled in Docker, AWS, CI/CD, and leading cross-functional dev teams.Known for clean code, pragmatic solutions, and delivering on time. Let’s build something great together.
Core
  1. DevelopmentAPIs & Backends: REST/GraphQL APIs, scalable microservices, clean architecture.
  2. Web Applications: Full-stack development with Node.js, NestJS, React, and Django.
  3. Data & Automation: PostgreSQL/MySQL, Redis, ETL pipelines, workflow automation.
  4. Cloud & Deployment: AWS, Google Cloud, Docker, CI/CD pipelines.
  5. Special Strengths: 8+ years backend + 5+ years full-stack experience.
  6. Track record modernizing messy/legacy systems into stable, maintainable platforms.
  7. Calm, thoughtful approach: I focus on sustainable, long-term solutions instead of short-lived hacks.
  8. Experienced in small teams/startups where flexibility and clarity matter.
What Clients Value
  1. I take ownership of complex tech challenges and bring clarity (“chaos-to-clarity”).
  2. I’m used to bridging between devs, data scientists, and business teams.
  3. I work independently but keep communication transparent and simple.


  1. Global availability, 100% remote. Available for freelance projects 20–40h/week. I ensure reliable overlap with EU mornings and partial US working hours for smooth collaboration. On-site work only considered for training/workshops on larger project budgets (100k EUR+)
Website

Languages

DeutschNative speakerEnglischFluent

Project history

Backend Developer

QUANTUM Int. GmbH & Co. KG (Client WiWin GmbH)

Internet & IT

10-50 team member

Project Summary
Led the backend/API track of a green investment platform, delivering a scalable Partner API and modern DevOps practices. Drove measurable improvements in system performance, developer efficiency, and user engagement by combining clean architecture with strong documentation and team enablement.

Tasks & Responsibilities
  • Conducted comprehensive code reviews on 100+ Git-managed submissions using advanced debugging, improving maintainability, scalability, and adherence to best practices — cutting bug rates by 25% and raising overall project quality.
  • Spearheaded the design and implementation of a high-performance Partner API using NestJS from scratch, ensuring seamless GraphQL ↔ REST integration and handling 500K+ requests/day with 99.99% uptime and 40ms average response time.
  • Developed and deployed a Customer Activity Tracking Solution with Google Analytics and Git, boosting engagement metrics by 40% for 1,000+ active users within the first quarter post-launch.
  • Established Git-managed documentation processes, streamlining onboarding and reducing training time by 30%, accelerating delivery by ~2 weeks per cycle.
  • Integrated PartnerAPI into the DevOps pipeline with Node.js, optimized SQL data structures, and implemented unit testing protocols — improving deployment frequency by 20%.
Tech Stack
NestJS · Node.js · GraphQL · REST · PostgreSQL · SQL · Git · Docker · AWS · Google Analytics · CI/CD

Senior Fullstack Developer

UpGuest Ltd.

Internet & IT

< 10 team member

Project Summary
Led the rebranding and fullstack overhaul of DailyPass into the UpGuest platform. Delivered new features, modern UI/UX improvements, and performance optimizations that drove higher engagement, reduced complaints, and created measurable revenue gains for hospitality clients.
Tasks & Responsibilities
  • Spearheaded the replication and rebranding of DailyPass into UpGuest, leading a fullstack initiative with Agile methodologies, Git, and modern UI/UX patterns — achieving a 40% increase in user engagement within three months.
  • Overhauled legacy layers with Agile and proven design patterns, adding 5 new functionalities and UI improvements across backend/frontend, managed via Git — reducing usability-related customer complaints by 30% in the first quarter.
  • Developed and integrated timeslot booking functionality with strong UI/UX focus, enabling cooking classes and optimizing hotel breakfast buffet capacity — boosting revenue by 20%.
  • Built document data extraction into online check-in flows, streamlining operations and reducing processing time by 40% across 10,000 monthly transactions.
  • Optimized system performance for mobile users, increasing engagement by 35% and driving significant growth in mobile booking conversions.
  • Migrated mapping features from Google Maps API to iFrame embeds, improving page load speed by 50% and supporting seamless usage for 5M+ users annually.
Tech Stack
Python · Node.js · React · JavaScript/TypeScript · PostgreSQL · Git · Agile · UI/UX Design · Google Maps API · iFrame Integration · Mobile Optimization

Senior Fullstack Developer

DailyPass

Internet & IT

< 10 team member

Project Summary
Key developer in building and scaling DailyPass, a SaaS platform enabling hotels to sell day-use amenities (e.g., pool access, gym memberships). Worked closely with leadership (CTO/CEO/CFO) to align technical delivery with business goals while leading feature development and developer coordination.

Tasks & Responsibilities
  • Platform Architecture: Evaluated and extended the Saleor E-commerce framework (Python backend, React storefront & admin) for hospitality-specific use cases.
  • Feature Delivery: Designed and implemented full-stack features for monetizing hotel amenities, directly boosting ancillary revenue streams.
  • Team Leadership: Created and managed Jira tickets, delegated tasks across developers, and provided ongoing mentoring and code reviews.
  • Stakeholder Alignment: Translated business requirements into actionable technical tasks and maintained progress reporting for executives.
  • Scalable Backends: Leveraged NestJS, GraphQL, PostgreSQL, Redis, and Google Cloud to ensure performant and reliable deployments.
Achievements
  • Drove the platform’s adoption across multiple hotel groups, contributing to 40%+ growth in user engagement.
  • Streamlined dev workflows with Git-based processes and CI/CD, reducing delivery cycles by ~20%.

Tech Stack
Saleor (Python, React) · NestJS · TypeScript · GraphQL · PostgreSQL · Redis · Express.js · GCP · Nginx · Agile (Scrum/Kanban)

Recommendations

"I highly recommend Frank-Dieter Stadtler, a skilled freelance software developer I've had the pleasure of working with. He led the development of a REST-to-GraphQL translation backend, integrating a partner company into our system, and made significant contributions to our main GraphQL backend. Frank demonstrated exceptional technical expertise, adaptability, and dedication. His documentation skills are outstanding, and his positive attitude made him a pleasure to work with."

WIWIN GmbH

Technical Lead Developer (Dominique Ramin Hummel)

"I highly recommend Frank as a skilled and reliable developer. I had the pleasure of working with him at DailyPass, where he consistently demonstrated exceptional technical expertise and problem-solving skills. Frank’s ability to communicate complex ideas clearly made him invaluable to the team, fostering collaboration and efficiency. Professional, dedicated, and proactive, he is an asset to any organization. Feel free to contact me for further details."

DailyPass

CMO (Friso M. Koopmans)

"Frank has been an important asset throughout our project, he has shown great skills with getting introduced into the project, understanding it and autonomously taking responsibility of parts of it, which he developed on. On a communication level, I enjoyed his detailed explanations and quick replies and have nothing to complain about!"

Wiwin GmbH

Head of IT (David Michel)

"I had the pleasure of working with Frank on Wiwin’s project. He was collaborative and easy to approach, we collaborated on pair programming, documentation, and code reviews. His extensive knowledge, calm demeanor, and patience when explaining concepts made him a great person to work with. Frank consistently delivers results, and I highly recommend him for any project."

Justrocket

Full Stack Developer (Daniel Zsiga)

"I got to know Frank as a very competent backend developer. He developed an API for us and always supported us with his experience and friendly manner. Frank is a team player. He also thinks outside the box. His Javascript expertise (NestJS) is outstanding, he can explain complex issues simply and is always available to advise all team members. I can recommend Frank without reservation."

wiwin GmbH

Head of IT

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