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Simon Wirtz

Freelance Backend Engineer, Kotlin/Java Expert

Works remotely from San Francisco

  • 37.778008
  • -122.431272
  • Suggested rate € 850 / day
  • Experience 7+ years
Propose a project The project will begin once you accept Simon's quote.

This freelancer is available part-time (3 days per week) but hasn't confirmed their availability in over 7 days.

Part-time, 3 days per week

Propose a project The project will begin once you accept Simon's quote.

Location and workplace preferences

San Francisco, CA, USA
Remote only
Primarily works remotely


Freelancer code of conduct signed
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Verified email


  • German

    Native or bilingual

  • English



Skills (10)

  • Languages
  • Beginner Intermediate Advanced
  • SQL
    Beginner Intermediate Advanced
  • Beginner Intermediate Advanced
  • Architecture

Simon in a few words

I am a freelance Software Engineer focused on backend development of scalable and distributed systems. I’m an expert for Kotlin and Java, containerization and product development.

I currently focus on Kubernetes, Serverless and I am excited about cloud-native software in general.
I've been working in Software for 10+ years and gathered experiences in different industries including travel, legal tech, online advertising, health and process automation. I'm also appearing in mentoring roles on various platforms and enjoy spreading my knowledge through different channels. I'm, among other things, an occasional international speaker, blogger, and contributor on StackOverflow. 👨🏼‍💻


Simon Wirtz

Digital & IT

Independent Software Engineer and Consultant - Kotlin and Java Expert

Cologne, NW, Germany

April 2018 - Today (4 years and 11 months)

I provide services around backend software development, content development, hiring scale, and general consulting. I have been working in the space for 10+ years and love learning new technologies. I'm an expert in Kotlin and Java, containerization, and product development.


Senior Interview Engineer, Mentor, Content Creator  - As a freelancer

Seattle, WA, USA

April 2018 - Today (4 years and 11 months)

Karat has conducted tens of thousands of technical interviews on behalf of enterprises and high-growth companies. Engineering and talent leaders who are searching for technical interview services or technical interview outsourcing partner with Karat to increase their technical interview capacity, while improving consistency, and new hire quality. After having conducted many interviews myself, I'm now mostly involved in helping to grow the community of Interview Engineers by mentoring new folks to get started on the platform. I also help test and develop new question sets that are used in Karat's various interview formats. I developed the company's first Knowledge Question set for the Kotlin programming language.


Senior Software Engineer

Berlin, Germany

August 2019 - August 2022 (3 years)

BRYTER is an enterprise no-code platform to automate decision-making knowledge. I worked with BRYTER as a Software Engineer to make their cloud-based SaaS product a success. Mainly, I was involved in enabling customers to integrate and connect their existing systems and tools with BRYTER by developing and publishing an integrations platform, thereby accelerating product adoption in general. I was involved in hiring efforts and took on leadership activities to help the company scale.

Exactag GmbH

Digital & IT

Software Engineer

Sand, Cologne, NW, Germany

July 2018 - July 2019 (1 year)

Exactag combines classic marketing mix modeling and digital marketing attribution to create a revolutionary new cross-media approach: marketing mix attribution. The result is a comprehensive platform for increasing efficiency across all digital and analog marketing activities. I worked with Exactag as a Software Engineer using Java, Kotlin, Groovy, Spring Boot, jOOQ, Hibernate, JPA, React, TypeScript, MySQL and other technologies to work on a multi-tenant data-driven SaaS application.

n-design GmbH

Software Engineer & Tech Team Lead

Cologne, Germany

August 2014 - July 2018 (3 years and 11 months)

n-design (now part of CompuGroup Medical) is a consulting company based in the eHealth sector delivering relevant products for the German eHealth market. I worked with n-design as a Software Engineer and technical team lead on their flagship product using technologies such as Java, OSGi, Spring, and Angular. Other relevant topics during my time at n-design included test automation, smart cards, eHealth, and release management. I had the temporary role of a tech lead working at n-design.

Amadeus Leisure IT GmbH

Junior Operations Internal Developer

Aachen, Germany

January 2014 - July 2014 (6 months)

Software development; Internal tooling using technologies such as Java, OSGi, Spring, Hibernate, JavaScript, MySQL, and MongoDB.

Amadeus Leisure IT GmbH

Apprentice Mathematical-Technical Software Engineer

Aachen, Germany

September 2011 - January 2014 (2 years and 4 months)