Lennart Rosam

Software Engineer · Based in Oldenburg, Lower Saxony, Germany


  • 👷 Backend over frontend
  • ☕️ Java over JavaScript
  • 📺 Terminal over GUI
  • 🛠️ DevOps / GitOps mentality
  • 🔒 Web-Security aware
  • 🐳 Dockerize all the things
  • ⛴️ Ship stuff through k8s, cloud run & co.
  • ☎️ Acquired interest for telephony (SIP/RTP) and 2G/3G/4G mobile Networks (SS7, DIAMETER)

This site is static HTML, dockerized and deployed to GCP via GitHub actions. Sources are available on GitHub.


Software Engineer (Remote)

sipgate GmbH

sipgate is a telephone company and Full-MVNO (Mobile Virtual Network Operator) based in Düsseldorf, Germany. As a software engineer on one of the core telephony network teams, I work on software components related to SIP telephony gateways as well as the 2G/3G/4G network core. Those are (micro) services that are mainly written in Java 8 - 17 and involves lower level handling of many "non-web" protocols like DIAMETER, SS7 and SIP.

April 2021 - Present

Backend Engineer (Remote)

MDM Münzhandelsgesellschaft mbH

MDM is an online retailer for collectors items, primarily coins and valuable metals like gold bars. As a lead engineer on the middleware team, I was responsible for developing microservices for things like credit scoring and handling of payments. Those were RESTFUL services that needed to integrate into MDMs existing SAP / ABAP based legacy core. It was my job to work with the SAP devs to engineer business requirements and identify problems.

I also helped to facilitate deployments of software to Google Cloud Platform in Kubernetes via HELM. The software stack was primarily PHP 7.3, Symfony and MySQL (CloudSQL).

June 2020 - March 2021

Software Engineer

Traum-Ferienwohnungen GmbH

Traum is an online marketplace for renting vacation homes all over europe. I was primarily in charge of maintaining the legacy monolithic core written in PHP 5. This involved "cutting back" the monolith on the path to a microservice based architecture and also updating the old core to newer versions of PHP (7.0), containerizing it, and making it cloud ready to be able to run it on Kubernetes (GKE).

I also had a focus on maintaining web security by fixing many potential security vulnerabilities and working on a team that pen-tested the software stack. We also had multiple external audits which I helped organize and provided technical assistance to the external pen testers.

May 2016 - May 2020

Unix System Administrator / Later: Backend Developer

MSP - Medien Systempartner GmbH

MSP is an agency delivering SAAS for customers in the newspaper publishing business. I started out as a system administrator for Unix systems where I maintained various servers based on SUN Solaris and Ubuntu Server.

I found my passion for software development here and later switched to the dev team as a backend engineer. I worked on developing the Java EE 8 backend for an iPad app, bringing the Bremen based WESER-KURIER newspaper onto the first iPad back when it was still a relatively new thing.

Based on the same technology, I also re-engineered the Browser E-Paper API for the Nordwest-Zeitung newspaper here in Oldenburg.

September 2010 - April 2016


Programming Languages & Tools
  • Cross Functional Teams
  • Agile Development & Scrum
  • Test Driven Development
  • Prefers self-organized environments #new-work

PGP Key & Email