Freelancer in Hamburg

Waldemar Kornewald

Hi, I'm Waldemar Kornewald - a freelance software engineer based in Hamburg, Germany. If you have complex code/bugs and need help designing easy to understand, maintainable code that prevents commonly recurring problems, please get in touch.

I'm available remote world-wide or on-site in Hamburg for:

  • Mobile apps: Android, Flutter, Kotlin, Java
  • Frontend: React, TypeScript, JavaScript
  • Backend: Python, Django, Flask
  • DevOps: Kubernetes, Docker, infrastructure-as-code
  • Architecture consulting

If you need help with one of your projects just contact me:


2020 – nowIBM: Android/Kotlin lead developer for IBM's electronic health record (ePA) and the CovPass app, security admission (gematik, BSI), end-to-end encryption, homomorphic encryption, multi-party computation, architecture, modernization of the codebase, teaching better development practices. Tech: Coroutines, Jetpack Compose, Kotlin Multiplatform, Ktor, kotlin.test, MockK, etc.
2017 – 2020Ovy: Flutter, Android/Kotlin/Java, Flask/Python, Bluetooth LE (custom thermometer), Dockerized dev env, Google App Engine, Redis
2017 – 2017SPIEGEL: Kubernetes setup/ops (on-prem & GKE), how-to-use workshops, Elasticsearch, PostgreSQL, Prometheus, Kibana, Grafana, Docker images for various services, etc.
2014 – 2020Locandis: Android/Kotlin/Java, React/TypeScript/JavaScript, Django/Python, Bluetooth LE (iBeacons), PostgreSQL, Redis, Docker
2015 – 2018sefibo: React/TypeScript/JavaScript, Django/Python, Elasticsearch, PostgreSQL, Redis, Docker, custom task queue
2014 – 2015Mainmetrics: Django/Python/SQLAlchemy, Python/JavaScript frontend, PostgreSQL, Redis, Docker
2008 – 2014various customers: Python, JavaScript, Django, Android, Java, Google App Engine, PostgreSQL, MySQL, Elasticsearch, MongoDB, Redis, C++
1999 – 2008various open-source projects: Python, Django, Trac, C++, Java, GPIB, WinAPI, Perl, PHP, x86 asm, USB HID

Open-source by Ensody®

Over the past 20 years I've also made several open-source contributions:

  • ReactiveState-Kotlin: Easy reactive state management for Kotlin Multiplatform. No boilerplate. Compatible with Android.
  • github/ensody
  • github/wkornewald
  • Django-nonrel: Fork of the Django web framework adding NoSQL support to its ORM (including backends for App Engine Datastore, Elasticsearch, MongoDB, etc.)
  • github/allbuttonspressed
  • Haiku: An open-source operating system project where I worked on PPP(oE) network protocols in the kernel, network settings app, website, Trac extensions/customizations, etc.
  • PyMeta 2: Parsing Expression Grammar (PEG) based on OMeta 2.
  • PyvaScript: Simple Python-inspired programming language that transpiles to JS. Implemented with PyMeta 2 (parsing raw text).
  • py2gpu: Python -> CUDA compiler. Implemented with PyMeta 2 (parsing the tree structure generated by Python's ast module).
  • pyjs: Optimizing, optionally typed Python -> JavaScript transpiler.
  • bitbucket/wkornewald