Michael 'Ruby' Kästner

Michael 'Ruby' Kästner

software architect and experimental physicist

Personal Data
Family name: Kästner
Birth name: Kleinert
Birthday: 5th of June 1989
Nationality: German
Parents: Prof. Dr. Dr. h.c. mult. Hagen Kleinert ,
Dr. Annemarie Kleinert
Technical Skills: TypeScript ECMAScript Node.js PHP SCSS SQL - stored procedures .NET MongoDB MySQL
Personal Skills: object-oriented software design relational database modeling financial markets (stocks, derivatives) nano physics solid-state physics quantum physics
Professional Activities
2022 - current: Deputy Head of Software Development at Doc Cirrus GmbH
2020 - 2022: Technical Project Leader at Doc Cirrus GmbH
2019 - 2020: Senior Software Developer at Doc Cirrus GmbH
2017 - 2019: Lead developer (DevOps) at Fonds Advisory Fa GmbH
2013 - 2017: Research Fellow at Freie Universität Berlin
2009 - 2017: Software developer at Fonds Advisory Fa GmbH
2006: IT-Manager of the 11th Marcel Grossman conference in Berlin
2005 - 2008: Lead developer (DevOps) and founder of the browser game "ArmyWars" (discontinued after 2015)
2012 - 2017: Ph.D., Freie Universität Berlin
2010 - 2012: M.Sc., Freie Universität Berlin
2007 - 2010: B.Sc., Freie Universität Berlin
1999 - 2007: Abitur, Hildegard-Wegscheider Oberschule

publications as a software architect



Medication Management Software
2019 - 2021: software architect and technical lead developer at Doc Cirrus GmbH, Berlin

"Medinspector®" is a medication management software for pharmacists and physicians, which is distributed as module for the practice management platform Doc Cirrus™ inSuite®. Being certified as medical device class I, the software fulfills high quality standards with respect to documentation, test coverage, and error handling. It comprises several microservices which share a common data model and interact through dynamic application interfaces.


front-end and back-end architecture, multiple microservices with shared code base, medical device certification class I, mongodb, NodeJS, GraphQL



Collaborative Portfolio Management Software
2017 - 2019: head of software development at Fonds Advisory Fa GmbH, Berlin

"Active.Portfolio.Tools" is a collaborative web-based portfolio management software, developed under my direction at Fonds Advisory Fa GmbH in Berlin. It is designed from scratch, to be a highly flexible and scalable platform, utilizing a broad range of state-of-the-art web technologies. Providing a full-scale desktop system within the web-browser as well as local client application, it allows a team of investment experts to manage multiple portfolios simultaneously for a wide variety of clients, each with individual investment strategies.


front-end and back-end design, micro services, scalable cloud technologies, HTML5, CSS3, SCSS, NodeJS, electron.JS, relational databases



Scientific Data Analysis Software
2013 - today: scientific researcher and Ph.D. student at the physics department of Freie Universität Berlin, Berlin

"SpectraFox" started as a tool simplifying the readability and management of data, recorded in physical experiments. No software existed for this specific purpose and type of data. The project evolved, and ended up as a full-scale data analysis platform. By now, it allows mass-treatment of data measured in different experimental setups and with machines of different manufacturers in various file formats. The usage scenario required reverse engineering of non-documented file types and efficient memory management. This led to a fast and flexible software. SpectraFox is published under an open source license.


.NET, mass data processing, data visualization, linear regression and non-linear curve fitting, multi-threaded architecture, CUDA and OpenCL parallelization, reverse engineering


Fonds Management System

Portfolio Management Software
2009 - 2017: lead developer at Fonds Advisory Fa GmbH, Berlin

The "Fonds Management System" (FMS) is a highly customized portfolio management software, written for the institutional investment company "Fonds Advisory Fa GmbH" in Berlin. The software is dedicated to simplify and automate repeating tasks, and to assist the fund managers in their investment decisions. Its most important feature is a framework, which ensures that all portfolios match the rules implied by the respective fund owners, by the supervising authorities, and by law.


.NET, WinForms, relational databases



Multiplayer Browser-Game
2005 - 2008: development and operation as high school student

The web-based multiplayer game "ArmyWars" was my first project. Thousands of players were online each day, searching for new challenges on the battleground, or hanging around with their friends. After high school graduation in 2008 the project was continued by a friend until 2015.

https://army-wars.de/ (discontinued in 2008)

PHP, JavaScript, relational databases

publications as an experimental physicist

My scientific articles are published under my official pseudonym "Michael Ruby".


Dr. Michael Kästner
Liebensteinstr. 6
14195 Berlin

privacy policy

The protection of your privacy and your personal data is one of our highest priorities.

Responsible contact for any questions regarding our privacy policy:
Michael Kästner, Liebensteinstr. 6, 14195 Berlin, GERMANY

Collection of general information

When you access this website through your web browser, the data of your specific request is submitted to our systems. The data contains the requested web page, the type of your web browser, your computer's operating system, the hostname of your internet service provider, and your current internet protocol address (IP address). The data itself does not allow a direct reconstruction of who you are. However, collecting the data is technically required to deliver the content of the page you requested to you. This is how the internet works. Since the protection of your privacy is one of our highest priorities, your data is not stored in a permanent way on our systems. All your data is deleted after delivering the requested content to you. Since the data is not stored on a hard disk, and just kept in our system's memory for the short time of your request, it becomes unlikely that, e.g., in the worst case of a successful cyber attack, your data may be compromised.

Transport encryption

All the data exchanged between your web browser and our systems is protected by modern encryption technologies (TLS).

When is your data deleted?

We collect data that is necessary to process your request and deliver the content to your web browser. The data is deleted immediately after the connection between your web browser and our systems is closed.

Your rights of information

You have the rights to be informed about all your data that is stored on our systems. Furthermore, you have the rights that we change or delete your data upon your request.

Changes to our privacy policy

This privacy policy may be changed in the future to always fulfill the laws. In any case, for each request of our website the currently valid privacy policy may be found on this page.