Freelance Java Developer Holger Pschera

I've been working now since more than 15 years in the Java environment with countless tools and frameworks in development, test and design/architecture: developing in customer projects, for standard products and frameworks and in various industries. Most of the time I know well what I'm doing and if not, I learn it quickly, actively take responsibility and contribute to discussions, questioning things and WoW, simply because work's more fun to me like that and I want to be part of a success, not just counting hours in a corner. I like to hunt the difficult bugs as I like to solve chess puzzles in my free time - or better, avoid them, by following my passion for readable, maintainable, reusable clean code and share this in the team: low coupling, clear naming and contracts/APIs, low cognitive complexity, and all that with strong focus on customers needs. I believe simplicity and readability are the keys to success, as well as understanding the customer(s) needs and perspective.

CV as PDF in english and german. (also as word document on demand)

I'm looking for new thrilling projects and opportunities starting in july 2025 on base of a freelance contract, as developer and/or architect, preferably longer than 6 months.

Living in Dresden/Germany I prefer projects nearby, but can also spend a week per month in more distant locations. Contact me via email at holger[at]pschera-software[dot]de, on LinkedIn or Xing.

liability insurance

personal information


age	39, born 1986
residence	Dresden/ Germany
contact	email: holger[at]pschera-software[dot]de
tax number/VAT	value added tax identification number (VAT No.): DE301268468

availability


when	starting at July or August 2025
where	For projects from three up to twelve months preferred in and around Dresden/Germany. A week per month in more distant cities is also fine, but then 75% should be remote time.
what	project support as freelancer in java development/architecture
payment	hourly rate on demand

projects and credentials

	click for details
09/2024 - 06/2025	AOK Systems: health insurance CRM systems
	company: AOK Systems industry: health insurance, CRM, contact center roles: Requirements analysis and development of SpringBoot Microservices as highly available Domain Services (System of Engagement) on top of SAP CRM Backend, e.g. Contact Management Archiving Service for TI-M Messenger, an identity service and one to route appointments and mails to external contact centers. Data synchronization to SAP backend via Kafka. Creating data models, business logic and REST-APIs, align on requirements with SAP engineers, POs and operators. Definition of public interfaces of the Digital Layer on top of oscare® product suite. programming languages and frameworks: JDK 21, SpringBoot 3.4, OpenAPI 3.1.0, Spring WebFlux tools: Kafka, KeyCloak, Postgres, Openshift, Kubernetes, ArgoCD, SAP S4/Hana, NexusIQ, Helm Charts web: www.aok-systems.com
09/2019 - 03/2024	ASML: semiconductor industry
	company: ASML industry: photolithography (semiconductor/ microchip manufacturing) description of company & team: Beneath its awesome hardware products ASML also stands for one of the biggest java communities in europe, part of it a small, but effective team of nowadays 30 members Dresden, to which I did contribute 4,5 years long. Roughly spoken: our services/products regularly gather big amounts of XML and binary data from the machines (scanner, metrology) in the fab, parse them, trigger calculations and provide all the results in various performant APIs to the frontend, where out customers can see in different diagrams what happens within the machines, where problems occur and how processes/ parts of tools develop: Giving insight helping to reduce waste and overlay. My various duties/roles within the team contained: Design, development and documentation of new product features in close collaboration with different specialized departments (LithoInsight). Migration of huge monolithic organized code base to container and microservice oriented architecture. Substantial research of domain logic, many maths and physics, migration of theoretical PoC Matlab code to Java on performant, highly available HVM environment. 2 years significant contribution and support of new platform and framework (using Neo4j, GraphQL, HDFS and Apache Spark) for uniform holistic lithography experience for customers in the fab: Alignment on designs with architects, test managers and product owners, hiring and onboarding, hundreds of code reviews, leading new team members amongst this jungle of complexity. Maintenance and extension of huge test suites: unit tests with mockito, component tests with test containers and stubs, contract tests, E2E-, performance & stress tests, check and maintenance of nightly build. Often deep analysis of test failures, race conditions, deadlocks etc. Often code reviews, trainings for new team members, taking around 20 job interviews. Facilitation of regular software design team meeting, leading discussions and workshops (sometimes for more than 30-70 people over multiple days). programming languages/ frameworks: Java 11, SpringBoot, SQL + QueryDSL, Liquibase/graph, Neo4j, GraphQL, JMS, AsciiDoc, OpenAPI 3.0/ Swagger, OData, JAX RS, JUnit5 tools: IntelliJ, Sonar, GIT, Maven, Jenkins, Bamboo, Bitbucket, Oracle, Postgres, HornetQ, Kafka, Docker, Apache Mesos/DC/OS, Testcontainer, Matlab, Spark, HDFS web: www.asml.com
04/2019 - 07/2019	SupplyOn (Newtron GmbH): Supply Chain Management
	industry: Supply Chain Management roles: development of SpringBoot Microservices in backend after Scrum. Creating data models, business logic and REST-APIs. programming languages and frameworks: Java SE 8, SpringBoot 2, JPA, Liquibase, UML, AsciiDoc, OpenAPI 3.0/ Swagger tools: IntelliJ, GIT, Maven, Docker, Jenkins, Bitbucket, RabbitMQ, Postgres, Keycloak web: www.supplyon.com https://www.newtron.de/en
09/2013 - today	Self-employed with Java-Software InstrumentDataAssistant (IDA)
	IDA is a tool for scientific measurement and comparison of musical instruments. It was initially based on violins. In this project I could cover all important stations of a software lifecycle by myself. The software gets improved permanently, but reached a stable state in 2016, when I extended my business in freelance projects. industry: musical instrument making, organology, genealogy roles: requirements engineering, design, implementation, coordination of partners, test, deployment, translation, marketing, sales, support and accounting programming languages/framewors: Java SE, Swing, JFreeChart, Batik, Hibernate, XML, SAX, JNI, SQL, Ant, Apache POI, Commons Math, JAI, JavaMail, Jaxen tools: Eclipse, SVN, Track+, ProGuard, AppBundler, Firebird, SQLite, DinkeyDongle, DBVisualizer, TeamViewer, Launch4j, IzPack further acquired skills: Deployment und UI guidelines of java applications on Mac OS X, experience with presentation at trade fairs and as lecturer, self-reliant project management web: www.ida-software.de (press)
07/2018 - 10/2018	Zedas GmbH: rail logistics
	industry: railroad freight transportation/ rail logistics roles: development of business logic in Java EE backend, arquillian tests, REST-Services programming languages: Java EE 7, Java SE 8 tools: Eclipse, JBoss EAP 7.x, Arquillian, Equinox, Docker, Jenkins web: https://www.zedas.com/
08/2016 - 03/2017	freelance java developer at T-Systems Multimedia Solutions in Dresden
T-Systems Multimedia Solutions	Implementation of an IOT interface adapter for communication between telematic control units (CTU) and a web portal industry: autmotive, telematics (IoT) roles: development, customer coordination, integration tests programming languages/framewors: Java SE 8, Spring Boot, RxJava tools: Eclipse STS, GIT, JIRA, Confluence, Jenkins web: https://www.t-systems-mms.com/
04/2011 - 01/2014	employed developer at GK Software
	Java development in projects and the standard product GKRetail, customizing, working in international project teams with customers from all over the world, installation and rollout of large software environments, conduction of trainings and workshops In-house and external in English, customer support, work in the SAP environment, specialist for LPP, MapForce, JasperReports, and a range of GK products. industry: retail roles: development, consulting, customer support, project management support location: Schöneck/Vogtland (GR) and Pilsen (CZ) programming languages/frameworks: Java SE, J2EE, Dependency Injection in connection with JMock in complex JUnit-Tests, Altova MapForce (interface mapping of SAP-IDocs for various customers in GKR-projects), JasperReports, RMI, Ant, Maven, div. XML Tools, many GK-In-house solutions tools: Eclipse, STS, SVN, PMD, Hudson, Track+, JIRA, Firebird, Oracle 10g, MS SQL Server 2008 R2, DBVisualizer, UltraVNC, DirectVNC, WinSCP, PuTTY, Total Commander, SAP R/3, VMWare, GKRetail, Tomcat, Apache ActiveMQ web: https://www.gk-software.com/ reference letter: 1 GK Software Zeugnis 2014.pdf (GR)
09/2007 - 01/2008	internship semester at EADS (European Aeronautic Defence and Space), project JoCCIS
	Creation of wizards for object generation according to NATO-MIP standard in a management control system using Java-Swing and hibernate. Some surface design for object storage via drag & drop. industry: management control systems/ armament roles: Java GUI development location: Friedrichshafen programming languages/frameworks: Java SE, Swing tools: Eclipse, SVN, codeBeamer, VMWare web: EADS Defence and Space (today Airbus DS)
10/2005 - 02/2010	computer science studies at the Westsächsische Hochschule Zwickau
	bachelor with focus on system development. location: Zwickau degree: Bachelor of Science (computer science) programming languages/frameworks: Java, Groovy/Grails, C/C++, Assembler, Xpath/XQuery/XML schema, AspectJ tools: Eclipse, SVN, CVS, MathLab, SPSS, SAP/R3, MS SQL Server 2005, eXist and much more. web: www.fh-zwickau.de

skills


languages	native language is german, fluent english (C1), basics in few other languages (CZ, PRT, FR)
previous responsibilities	Java software development, design & test Backend Java development with lots of tools and frameworks: JEE, Spring Boot, JAX/RS, SQL/JPA/Spring Data, JMS, GraphQL, Neo4j, Docker, Spark, ...), reactive programming (RxJava, Spring WebFlux), asynchronous architectures (Kafka, JMS) Architecture & design, alignment with customers, internal departments, product owners, test manager & architects, creating technical documentation, charts, holding presentations/workshops and facilitate regular team meetings & discussions (as substitute of scrum master) Automated tests: JUnit 4 & 5 with Mockito, Component/IT with test containers and Mockservers, contract tests with stubs, performance-, stress- & E2E-Tests, checking and maintaining the nightly build, test data, performing FST analysis Team coordination: Taking job interviews, help during onboarding, do tons of code reviews, technical and functional KTs, hosting a mindset of shared responsibility within the team more distant in the past also frontend: lots of Swing (for GK, IDA), little JavaFX, JSF and SWT, JavaScript/Typescript + React
industries I know:	Always eager on new exciting industries. So far: retail, logistics, IoT, microchip manufacturing, health insurance & CRM, defense
programming languages	more than 15 years of experience with Java, SQL, XML und HTML Basics in C/C++, Assembler, JavaScript, PHP, Batch and Shell scripting, Ant
operating systems	Windows XP-11, Linux Ubuntu, Mac OS X from 10.6
development tools/ IDE/ Lifecycle	I used to work a lot with IntelliJ, Eclipse, STS, Maven, JIRA, Confluence, Bitbucket, GIT, Docker, Jenkins, Bamboo and Nexus. Experiences in using Putty, WinSCP, VNC, ELK-Stack, Splunk, VisualVM etc. to go on bug hunt in test and production systems (on prem, azure, VMWare). Clean Code Tools and principles like SonarQube, PMD, CheckStyle, jQAssistant, Code generators, PR reviews, Single Responsibility and Test Driven Development are daily routine since many years. From simple unit test up to complex IT and system E2E tests I know many tools(JUnit, Mockito, JMock, Arquillian, Testcontainer ...). Several other tools I often use: Postman, Jailer, Swagger, VisualVM, Total Commander.
databases	Postgres, Oracle, SQLite, Firebird und MS SQL are the relational DBMS I mostly worked with. In addition, I gained experience with graph databases (Neo4J, Cypher and above GraphQL as API layer) as well as Hadoop File System and (long ago) with XML-Databases (eXist, XQuery).
Java frameworks/libraries/ tools	Java until Version 11, JEE and Spring. Spring Boot, Spring Data, JPA+Hibernate, QueryDSL, Liquibase, Liquigraph JAX-RS, Jackson, JMS & AMQP (with ActiveMQ, RabbitMQ, HornetQ), Kafka, CDI, JNDI, JAXB & JAXP, JavaMail, JTA, Swing, JSF, JNDI, JBoss, Tomcat, Arquillian, JDBC, JFreeChart, Batik, JNI, JUnit, Mockito, RXJava, Spark, Testcontainer, Mockserver, Resilience4j ...
virtualization and container	Since 2018 mainly via container and several orchestration tools such as Apache Mesos/DC/OS, OpenShift, Kubernetes. Earlier mainly via VMWare Tools and VirtualBox on Mac.
others tools	Postman, Total Commander, Tortoise, SmartSVN, Altova MapForce, JasperReports, AppBundler, DBVisualizer, IzPack, FreeMind, VisualVM, Jailer, Confluence, Sharepoint, MS Teams and many more.
hardware programming	I've collected some experiences with hardware interfaces for point of sales (JavaPOS). Additionally, I made the IK220 of Heidenhain work in java.

other


further interests	dance, books, poetry, music, nature, meditation