Seite wählen

You are searching a Developer / Architect?

I want to develop state of the art and innovative high quality and tested software in order to make users and clients happy.


Hire MeView My Work

About Me

Hello, my name is Markus Lehmann.
I am a senior mobile developer with backend expierence!

I am developing software for more than 16 years. In the last six years I have found my passion in developing mobile apps. Most of the time for Android.

I have worked for more than four years as a Senior Consultant in the Health Sector at IBM. I have done architectureal designs, development and several client integrations.

Back then my most interesting project was the electronic health record system known in Germany as „elektronische Gesundheitsakte“ (eGA) and „elektronische Patientenakte“ (ePA).

Flutter is the new fire in the Cross Plattform world. In the beginning of 2020 I started to develop AlarmBoard, a flutter app for the emergency sector. Our backend is hosted at AWS.


  • Android
  • Kotlin
  • Java
  • Rx Kotlin / RX Java
  • Dagger 2
  • LiveData, Room, MVVM
  • AWS Lamda, EC2, Cognito, ..
  • Flutter / Dart
  • iOS, Swift, Objective C
  • Angular JS
  • PHP
  • Javascript, Typescript, CSS, HTML
  • SAP UI5
  • Capacitor
  • UML
  • OpenID, OAuth 2.0
  • SQL
  • Keycloak
  • Hibernate, JPA
  • Python
  • Spring

Architectural Thinking

Issued by IBM

Attaining this badge demonstrates the ability to provide a repeatable and consistent approach to developing IT architectures via a common thought process that enables Architects to communicate and work together based on a common set of artifacts. The audience for this badge is primarily Architects and other IT professionals acting in the role of an Architect.

Ready to start a project?

I’m available for freelance hiring

Tuchtweg 18, 26129 Oldenburg

My Vision

Software has to be reliable, maintainable and open for further development.

For good software it is essential to step back to see the overall solution.

Choosing the correct architecture, framework or approach should be based on the current state of the software, the skillset of the people involved, state of the art and the circumstances around the project. You do not want to do a software island which is the state of the art but not maintainable.

To me an architect has to be part of the team. As an architect I am leading by example. I have an understanding about the used technologies, alternatives, their pros and cons and the requirements.

I know the systems around me and how they are interacting with each other.

I believe software development is  a circle I define, design,

build, test, …


I need to know the current situation and circumstances.

Therefore I have to step back to see the overall context before I design the solution.

I have to get to know the product, the requirements, depenedencies and circumstances.


The architecture of software is key for maintainability, testability and further development.

Doing software is not only about implementing and building.

The architecture defines the basement for further developments.

Key components and flows should be get designed e.g. in UML and get documented.


I want to build state of the art, innovative, high quality software.  Therefore I am continuesly learning, watching, listening and communicating with other developers.

I have a passion for building software until I have developed 2D games in C++ 16 years ago and the learning has never stoped.


Testing software is key to grantee the development success, stability and reliability.

If I am new to a project without tests, I would start doing UI Test to define a basline for further development.

Developing software is like fighting fire

In my spare time, I am a voluntary firefighter.

As a platoon leader of the CBRN defense forces of the city of Oldenburg I am responsible for up to 32 fire fighters in 7 vehicles.


In emergency situations I can grow on my expierience and training where I recce, evaluate, plan, command and inspect.


At you can learn more about my spare time activities and how you can support your local voluntary firefighters.

Senior Consultant

@IBM Deutschland
January 2017 – March 2021

I have started in 2017 as a Consultant
Since August 2019 I have worked as a Senior Consultant

eGA / ePA

Senior Android Developer / Senior Consulant
August 2017 – March 2021

I have designed and developed core components of the electronic health record system known in Germany as „elektronische Gesundheitsakte“ (eGA) and „elektronische Patientenakte“ (ePA) in a multi team context. I did architectures, Android native development as well as client facing presentations and workshops. I have backed five client integrations. I was the contact point for a major private insurance company.

Key Technologies

  • Kotlin
  • RxKotlin / RxJava
  • Dagger2
  • Retrofit
  • Coin
  • Android Architecture Components
  • UML
  • Clean Architecture
  • OpenID
  • Keycloak
  • Capacitor

iOS Medication Plan App

iOS Developer
January 2017 – June 2017

I have extended an iOS app and framework which have been integrated in several client apps.

Key Technologies

  • Swift

Partner / Founder

@Solance GbR
January 2020 – Today

Solance GBR is a company which I have founded together with Erika Root, Helge Horoba and Maik Buse to develop  and distribute mobile applications.

AlarmBoard App

January 2020 – Today

AlarmBoard is a mobile app for Android and iOS to keep track about staff during emergency operations. It can manage an emergency organisation like a firebrigade. Since 2019 my firebrigade is using AlarmBoard to keep track of our staff and operations.

For several years I have tested new implementations and architectures in the app as well as in the cloud using AWS. The app was a playground on which I could grow as a developer.

In the beginning of 2020 my teammates joined me and we started to test Flutter.

I have done all the architectural work off the app and the backend and guided my collegues through the development process.

Due to the layer architecture of the app we could easily exchange some of the layers by using flutter. In mid 2020 we have droped all Kotlin code and switched to 100% Dart.

Key Technologies

  • Flutter
  • Dart
  • AWS Cognito, Lamda, ..
  • UML
  • Clean Architecture
  • Android Architecture Components
  • Kotlin

Junior Consultant

@BTC Business Technology Consulting AG
October 2015 – December 2016

Enterprise Application Software

Frontend / Backend Developer
January 2016 – December 2016

In a small Scrum team I have developed the frontend, backend and database of a system of the energy sector.

Key Technologies

  • Java
  • Spring
  • JPA, Hibernate
  • Oracle SQL
  • Typescript
  • Angular JS

SAP UI5 Application

Frontend Developer
In 2016

In a small team I have developed an SAP UI5 application.

Key Technologies

  • Javascript
  • SAP UI5

Android and iOS Apps

iOS Developer / Android Developer
October 2015 – December 2016

I have maintaned and extended four Android and iOS apps.

Key Technologies

  • Objective C
  • Java

Research Assistent

@Carl von Ossietzky Universität Oldenburg
October 2014 – August 2015


I have lead several seminars in the context of algorithms and programming.

Research Assistent

@OFFIS – Institut für Informatik
September 2013 – August 2014

Physical package transportation system

October 2015 – December 2016

I have concepted and developed transportation systems.

Key Technologies

  • C
  • Siemens SIMATIC S7

Student Assistent

@Carl von Ossietzky Universität Oldenburg
October 2010 – August 2013


I have lead several seminars in the context of algorithms and programming.

My voluntary work

Fire Fighter

@City of Oldenburg
2012 – today

I am a voluntary fire fighter at the firebrigade Haarentor.
In addition to the usual fire fighter training I am trained in CBRN defense and the leaderships of platoons of firefighters.

CBRN Defense

Platoon Leader
September 2016 – today

During emergency operations I am reponsible for 32 fire fighters in seven vehicles.

CBRN Defense

Squad Leader
January 2014 – August 2016

During emergency operations I was reponsible for 18  fire fighters in four vehicles.

CBRN Defense

Squad Member
2012 – December 2013

During emergency operations I was reponsible for 18  fire fighters in four vehicles.

Voluntary Member

@Niedersächsische Jugendfeuerwehr e.V.

I am a voluntary operative of the youth fire brigade of Lower Saxony. Today I am reponsible for the public relations of the country Weser-Ems.

Public Relations

Public Relations Manager of the county Weser-Ems
April 2011 – today

During emergency operations I am reponsible for 32 fire fighters in seven vehicles.

Administrative District Leer

April 2009 – February 2013

City of Leer

January 2009 – September 2011

Fire Fighter

@City of Leer
January 2001 – 2012

I was a voluntary fire fighter of the city of Leer.

CBRN Defense

CBRN Squad Member of the District Leer
2010 – 2012


Fire Figther
2008 – 2012

Youth Firebrigade

Youth fire figther
January 2001 – 2008