Maximilian Fellner

Maximilian Fellner



Software Development Manager Zapp

Technical manager for two full-stack teams in the customer-facing domain of an early-stage e-commerce startup.


  • Successfully scaled two teams from 4 to 8 engineers by hiring and onboarding.
  • Mentored and coached engineers through regular 1-on-1 meetings and by setting personal development objectives. Conducted routine performance reviews with feedback on achievements and improvement areas.
  • Developed role descriptions and technical interview process for SDE, SDM, and QA positions.
  • Improved team effectiveness by establishing and running agile ceremonies, including dailies, planning meetings, retrospectives, and sprint reviews.
  • Set up and supervised mature software lifecycle processes, including, technical writing and architecture documentation with C4-modelling, testing (unit, integration, end-to-end, performance) build- and release-automation, observability, on-call, and incident management.
  • Set up end-to-end observability of important service-level indicators to find critical performance bottlenecks in the frontend and backend using Sentry and Cloud Trace.


  • Created dedicated backend for frontend and with a GraphQL API for product search and presentation backed by Elasticsearch. Used InversifyJS to implement an Inversion of Control pattern. Utilized Jest for unit- and integration-testing, K6 for load- and stress-testing. Other technologies used: Google Cloud platform, serverless cloud functions, Pub/Sub, TypeScript.
  • Developed Zapp mobile app for Android and iOS with React Native, TypeScript, GraphQL, and Firebase.
  • Replication of cloud infrastructure across multiple separated markets and geographic regions with the help of Terraform.

Tech Lead in Support Applications N26

Technical lead of 2 teams working on critical back-office solutions for the bank: one full-stack (TypeScript) and one backend (Kotlin) team.

Achievements & projects

  • Responsible for the technical design & architecture of internal web applications and automation systems.
  • Established consensus on system design between our team and others by conducting an event storming exercise.
  • Instructed other team members as a mentor and coach. Helped them with their personal development by providing feedback in regular 1-on-1 meetings.
  • As a hiring manager of the team, responsible for the interview process.

Senior Full-Stack Developer in Internal Tools N26

Senior full-stack developer in a team creating the applications for the internal users of the bank.

Achievements & projects

  • Designed and developed a micro frontend framework and platform for internal web applications with React, TypeScript, GraphQL, and Node.js.
  • Developed an IAM system for web applications with React, TypeScript, and Node.js.
  • Developed and maintained multiple Node.js microservices.

Software Engineer in API Management Zalando SE


  • Built and maintained microservices using Java, Go, and Node.js, deployed on Kubernetes.
  • Designed and developed user interfaces of web application frontends.
  • Published technical narratives and guidelines for all technology teams, including the RESTful API and Event guidelines.


  • API Portal, a website to discover API specifications based on Node.js and React.
  • API Discovery, a fleet of microservices to collect API specifications written in Java and Go.
  • Zally, a linter for OpenAPI (Swagger) REST API schemas, written in Kotlin.

Software Engineer in Brand Solutions Zalando SE


  • Developed and maintained full-stack web applications deployed on Amazon Web Services.
  • Agile and test-driven software development in an autonomous team.
  • Maintained the complete product lifecycle including continuous monitoring and troubleshooting.


  • Brand CMS, a content management system for business customers with a RESTful microservice architecture using Java, Angular, and PostgreSQL.
  • Tessellate, a server-side webpack bundler and React renderer for Mosaic built with Node.js.
  • Zappr, an open-source GitHub integration written in React and Node.js.
  • Aggregated and analyzed business data using the SciPy stack, including Pandas.
  • Built a prototype for analyzing Kafka-based event data in a Hadoop data lake using Hive queries.



Master of Science – Graz University of Technology, Austria

Software Engineering and Management Master’s thesis at the Institute of Software Technology on behavior-driven development and specification by example of visual programming languages.


Bachelor of Science – Graz University of Technology, Austria

Software Development and Business Management Bachelor’s thesis at the Institute of Software Technology on the test-driven development of ‘Catrobat‘, a visual programming language for Android.


Matura – Handelsakademie Lambach, Commercial Academy, Austria

Specialized in Commerce and Information Technology


2017 Convolutional Neural Networks

2017 Structuring Machine Learning Projects

2017 Improving Deep Neural Networks

2017 Neural Networks and Deep Learning


École Polytechnique Fédérale de Lausanne: Functional Programming in Scala Specialization


École Polytechnique Fédérale de Lausanne: Functional Programming Principles in Scala


École Polytechnique Fédérale de Lausanne: Functional Program Design in Scala


École Polytechnique Fédérale de Lausanne: Parallel programming


Delft University FP101x: Introduction to Functional Programming

Programming languages

  • JavaScript & TypeScript (7 years experience)
  • Java & Kotlin (5 years experience)
  • Python (4 years experience)
  • Go (1 year experience)
  • Scala (1 year experience)
  • C/C++ (1 year experience)

Frameworks & tools

  • Node.js (7 years experience)
  • React (6 years experience)
  • GraphQL (4 years experience)
  • Docker (5 years experience)
  • AWS (6 years experience)
  • Google Cloud (1 year experience)
  • PostgreSQL (6 years experience)
  • Elasticsearch (2 years experience)


  • German (native language)
  • English (fluent in written and spoken language)
  • French (basic skills)

On the web