Stefan Baust - Senior Full Stack Developer / Co-Founder / CTO / Head of Development

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Nußloch, Germany

Experience

Mar 2023 - Present

2 years 5 months

Düsseldorf, Germany

Senior Full Stack Developer / Co-Founder / CTO / Head of Development

Netprint Development & Solutions GmbH

Technical overall responsibility for innovative SAP Customer Checkout solutions at leading clients like Aramark, Consortium Gastronomie, Feinkost Käfer, TSG Hoffenheim, and VfB Stuttgart. Full lifecycle support from requirement analysis to implementation and support.
Successfully designed and developed the NDS SmartPOS platform ("Runner App"):
Designed the software architecture and implemented it following "Modern Android Development" principles.
Led a small development team (1 Android expert, 1 working student) with 50% custom development.
Integrated various payment SDKs (S-Payment S-POS, VR Payment, CCV), enabling clients to save significant costs by reusing existing contracts.
Successfully rolled out to multiple major clients with proven increased efficiency of sales staff.
Independently developed and implemented critical infrastructure components:
Reporting server (SQL, JasperReports): Reduced accounting effort by eliminating daily manual transfers to the ERP system.
ZVT plugin: Solely implemented the serial protocol using Java/Netty over TCP/IP.
Saved clients several thousand euros per location by replacing proprietary solutions with the ZVT plugin.
In production at several Bundesliga stadiums handling high transaction volumes per match day.
Fully developed specialized plugins and server apps to extend SAP Customer Checkout:
Waiter Teams plugin: Allows teams of waiters to work and settle together.
SQL Reporting: End-to-end design and full documentation.
RFID payment solution for staff cards: Managed the full development cycle.
Integration with reservation services: Designed and co-implemented seamless connections to "Luca" and other services.
Provided direct on-site technical support with clients, including:
Fast troubleshooting in high-volume live environments.
Close collaboration with stakeholders to continuously improve systems based on real-world feedback.
Tools and technologies: Java, JavaScript, TypeScript, Kotlin, HTML5, CSS, SQL, Shell, Spring Framework, Spring Boot, Spring Security, Angular, RxJS, Vue.js, Bootstrap, Vaadin, Hibernate, Android, Unit Testing, JUnit, Mockito, Dagger, Hilt, Sentry, REST, SOAP, OData, WebSockets, MQTT, RabbitMQ, Apache Camel, Apache CXF, Apache FOP, Apache PDFBox, Swagger, OpenAPI, JSON, XML, RAG, LLMs, OpenAI API, GPT-4, Nginx, Nginx Reverse Proxy, Docker, Docker Compose, Portainer, Kubernetes, HELM, Git, GitHub, Bitbucket, Jenkins, SonarQube, Snyk, OWASP Dependency-Check, DevSecOps, DevOps, PostgreSQL, SAP HANA, Apache Derby, Microsoft SQL Server, SSRS, JasperReports, Linux, Windows Server, Hetzner Cloud, AWS, S3, SAP Customer Checkout, POS systems, ERP, Payment SDKs, Dallmayr Pay, ZVT, ACI e.Socket, RFID, Mifare, Netty, jSerialComm, OAuth2, OpenID Connect (Keycloak), JWT, Auth0, Supabase, Maven, Gradle, IntelliJ, UML, Agile, Scrum, CI/CD, TDD, Jira, Confluence, Asana, Microsoft Office

Aug 2021 - Present

4 years

Dublin, Ireland

Remote

Freelance Senior Full Stack Developer (Remote)

TRC-Solutions LTD

Comprehensive technical consulting for optimal implementation of SAP Customer Checkout, including requirement analysis, solution design, and best practices for customer success.
Independently designed and developed critical payment solutions:
Full architecture and implementation of terminal integrations for Clover, GlobalPay US/UK, and ACI Payments.
Developed from prototype to production-ready solution, including extensive component testing.
Delivered fully documented and tested solutions to the client for final approval with payment providers.
Built custom enterprise solutions:
SQL Reporting with automated (S)FTP upload: Designed data architecture and implemented the full workflow.
VIP customer management: Developed a plugin to automatically assign VIP discounts and credits in retail and food & beverage contexts.
Managed all project phases independently from requirement analysis to architecture, coding, handover, and support.
Tools and technologies: Java, JavaScript, TypeScript, HTML5, CSS, SQL, Shell, Spring Framework, Spring Boot, Spring Security, Angular, RxJS, Vue.js, Bootstrap, Vaadin, Hibernate, Unit Testing, JUnit, Jasmine, Karma, Jest, Cypress, E2E Testing, Protractor, Playwright, Mockito, REST, SOAP, OData, WebSockets, MQTT, RabbitMQ, Apache Camel, Apache CXF, Swagger, OpenAPI, JSON, XML, XSL, Nginx, Docker, Docker Compose, Git, GitHub, Bitbucket, Jenkins, SonarQube, DevOps, Snyk, OWASP Dependency-Check, DevSecOps, PostgreSQL, Microsoft SQL Server, SAP HANA, Apache Derby, JasperReports, Linux, Windows Server, SAP Customer Checkout, POS systems, ERP, Payment SDKs, OAuth2, OpenID Connect, JWT, Auth0, Maven, Gradle, IntelliJ, UML, Agile, Scrum, CI/CD, TDD, Jira, Confluence, Asana, Microsoft Office

Jul 2021 - Sep 2021

3 months

Stuttgart, Germany

Remote

Freelance Senior Full Stack Developer (Remote)

Leading Transmission System Operator in Baden-Württemberg

Targeted development on a cloud-based coordination platform for grid stability:
Implemented key frontend features in Angular (paging, additional views).
Significantly increased test coverage in the Spring Boot backend.
Quickly onboarded and efficiently delivered according to requirements and standards.
Tools and technologies: Java, JavaScript, TypeScript, HTML5, CSS, SQL, Shell, Spring Boot, Spring Framework, Spring Security, Angular, RxJS, NgRx, Hibernate, Unit Testing, JUnit, Jasmine, Jest, Karma, E2E Testing, Protractor, Playwright, Cypress, Mockito, REST, Swagger, OpenAPI, JSON, Docker, Git, GitHub, Jenkins, DevOps, DevSecOps, Microservices, PostgreSQL, Linux, Windows Server, OAuth2, OpenID Connect, JWT, Maven, IntelliJ, UML, Agile, Scrum, CI/CD, TDD, Jira, Confluence, Microsoft Office, Energy Sector

May 2021 - Mar 2023

1 year 11 months

Düsseldorf, Germany

Freelance Senior Full Stack Developer

Netprint Datensysteme GmbH

Strategic consulting and technical lead for implementing SAP Customer Checkout, with deep understanding of business needs and technical options.
Fully independent development of mission-critical plugins and server apps:
End-of-day plugin: Reduced closing time by about 70%, offering major operational benefits for large events.
Pioneer development of the Waiter Teams plugin: Designed and implemented for the first use at Oktoberfest.
SQL-based reporting system: Complete architecture and implementation of a custom reporting framework.
On-site technical support with clients, including:
Fast troubleshooting in high-volume live environments.
Close alignment with stakeholders to continuously improve the systems based on real-world use.
End-to-end responsibility for the entire development cycle from initial concept through architecture, coding, testing, documentation, and maintenance.
Tools and technologies: Java, JavaScript, TypeScript, Kotlin, HTML5, CSS, SQL, Shell, Spring Framework, Spring Boot, Spring Security, Angular, RxJS, Vue.js, Bootstrap, Vaadin, Hibernate, Android, Unit Testing, JUnit, Jasmine, Karma, Jest, Cypress, E2E Testing, Protractor, Playwright, Mockito, Dagger, Hilt, Retrofit, Room, REST, SOAP, WebSockets, MQTT, RabbitMQ, Apache Camel, Apache CXF, Swagger, OpenAPI, OpenAI API, GPT-4, JSON, XML, XSL, Nginx, Nginx Reverse Proxy, Docker, Docker Compose, Portainer, Git, GitHub, Bitbucket, Jenkins, DevOps, PostgreSQL, Microsoft SQL Server, SAP HANA, Apache Derby, SSRS, JasperReports, Linux, Windows Server, Hetzner Cloud, SAP Customer Checkout, POS systems, ERP, Payment SDKs, Dallmayr Pay, ZVT, ACI e.Socket, RFID, Mifare, Netty, jSerialComm, OAuth2, OpenID Connect, JWT, Auth0, Maven, Gradle, IntelliJ, UML, Agile, Scrum, CI/CD, TDD, Linux, Jira, Confluence, Asana, Microsoft Office

Jan 2021 - Mar 2021

3 months

Mainz, Germany

Freelance Senior Full Stack Developer

C24 Bank GmbH

Interim support as part of a taskforce for the website and web app, including adding animations, updating content and styling, and extending web app functionality.
Tools and technologies: JavaScript, TypeScript, HTML5, CSS, Angular, RxJS, NgRx, Scully, Unit Testing, Jasmine, Jest, Karma, E2E Testing, Protractor, Playwright, Cypress, Selenium, REST, Swagger, OpenAPI, JSON, Traefik, Docker, Git, GitHub, Bitbucket, Jenkins, IntelliJ, UML, Agile, Scrum, CI/CD, TDD, Jira, Confluence, Microsoft Office

Dec 2019 - Jan 2020

2 months

Heidelberg, Germany

Freelance Senior Full Stack Developer

BUNG Ingenieure AG

Technical design and implementation of a web application prototype for interactive display of current construction projects.
Tools and technologies: TypeScript, JavaScript, OpenLayers, Electron, HTML5, CSS

Jun 2019 - Jul 2019

2 months

Hamburg, Germany

Remote

Freelance Senior Full Stack Developer

hokona GmbH

Remote support for UI development of the "CCO Customer Display".
Tools and technologies: Angular, Java, JavaScript, TypeScript, SAP Customer Checkout, HTML5, CSS

Feb 2019 - Dec 2023

4 years 11 months

Walldorf, Germany

Freelance Senior Full Stack Developer

SAP SE

Developer in the core team of the SAP Customer Checkout POS system:
Implemented complex feature extensions for the new frontend (NGUI) based on Angular and SAPUI5.
Co-developed interfaces for third-party integrations, significantly boosting product flexibility and market relevance.
Actively contributed to architecture decisions and successfully implemented shared concepts.
Improved product quality and stability:
Conducted code reviews to ensure code quality and compliance with corporate standards.
Participated in agile processes including sprint planning, daily scrums, and retrospectives.
Continuously integrated development results into the codebase following CI/CD principles.
Other responsibilities:
Collaborated effectively in an internationally distributed team.
Documented implementations and architectures for sustainable knowledge transfer.
From 2021 provided part-time support.
Tools and technologies: Java, JavaScript, TypeScript, HTML5, CSS, SQL, Shell, Spring Framework, Spring Security, Angular, RxJS, NgRx, SAPUI5, EclipseLink, Unit Testing, JUnit, Mockito, Jasmine, Jest, Karma, E2E Testing, Protractor, Playwright, Cypress, Selenium, SonarQube, DevSecOps, REST, SOAP, OData, WebSockets, Apache CXF, Swagger, OpenAPI, JSON, XML, XSL, Apache FOP, Docker, Git, GitHub, Jenkins, DevOps, Microsoft SQL Server, SAP HANA, Apache Derby, Linux, Windows Server, SAP Customer Checkout, POS systems, ERP, Payment SDKs, Netty, jSerialComm, OAuth2, OpenID Connect, JWT, Maven, Gradle, IntelliJ, UML, Agile, Scrum, CI/CD, TDD, Linux, Jira, Confluence, Microsoft Office

Jul 2018 - Jan 2019

7 months

Heidelberg, Germany

Consultant

BridgingIT GmbH (formerly Heidelberg mobil International GmbH)

Expanded the Spring Boot backend for electromobility for a publicly traded energy company and co-designed and implemented an Angular-based portal for managing charging stations and electric vehicle fleets.
Tools and technologies: JavaScript, TypeScript, HTML5, CSS, SQL, Java, Spring Boot, Spring Framework, Unit Testing, JUnit, Angular, RxJS, NgRx, Angular Material, REST, Jasmine, Jest, Karma, E2E Testing, Protractor, Selenium, Webpack, OAuth2, OpenID Connect, JWT, JSON, MongoDB, NoSQL, Microservices, DevOps, DevSecOps, Microsoft Azure, Azure App Service, Azure API Management, Azure Application Insights, Service Bus, Azure DevOps, Git, CI/CD, Maven, IntelliJ, UML, Agile, Scrum, TDD, Jira, Confluence, Microsoft Office, Energy Sector, CPO, EMP

Feb 2012 - Jun 2018

6 years 5 months

Heidelberg, Germany

Software Developer

Heidelberg mobil International GmbH

Contributed to a networking feature for a trade fair app that helped over 2,500 people network better. Coordinated with clients and external developers, integrated the app with a backend, and implemented the Android version.
Implemented a mobile form management app and web frontend using Ionic and AngularJS, and integrated Keycloak as an OAuth2 provider. Worked closely in a Scrum team with backend, frontend, and QA developers to align requirements.
Played a key role in Deep Map™ WebSDK v2+, simplifying indoor map integration for clients. Selected technologies, designed architecture, and re-implemented components using the latest OpenLayers, TypeScript, and modern tools.
Connected third-party services (SOAP, REST) from client systems in the trade fair environment to sync user data between website and mobile app.
Automated the configuration of trade fair web apps, saving significant time. Enhanced an existing Excel parser and achieved near full automation of configuration with Jenkins.
Tools and technologies: Java, Kotlin, Groovy, Shell, Spring Framework, Spring Boot, Spring Security, Grails, Hibernate, Unit Testing, JUnit, REST, SOAP, JavaScript, TypeScript, HTML5, CSS, Angular, Jasmine, Jest, Karma, Android, RxJS, E2E Testing, Protractor, Selenium, Ionic, Cordova, Retrofit, Room, OpenLayers, JSON, XML, OAuth2, OpenID Connect, JWT, Keycloak, PostgreSQL, PostGIS, Elasticsearch, NoSQL, Zuul Proxy, Apache2, Docker, Maven, Apache CXF, Microservices, Agile, Scrum, CI/CD, Git, SVN, TDD, UML, Linux, Jira, Confluence, IntelliJ, Microsoft Office

Oct 2008 - Feb 2012

3 years 5 months

Mannheim, Germany

Internships during dual studies, Software Developer

sobedi GmbH / apinso GmbH

Internships during dual studies. Focused on designing and implementing requirements in Java and Groovy (backend and frontend). Then worked full-time as a software developer at apinso GmbH.
Implemented a domain-specific language based on Groovy, allowing Excel-like formulas.
Built a tool to automatically compare application databases to ensure successful data migration.
Automated application deployments using Apache Ant.
Tools and technologies: Java, Java EE, Groovy, EJBs, Hibernate, JUnit, Selenium, HTML5, CSS, ZK Framework, Eclipse RCP, IBM DB2, SQL, REST, SOAP, JSON, XML, XSL, Apache Ant, iText, JBoss, Git, SVN, Mercurial, Lotus Notes, Microsoft Office, Eclipse, TDD, UML

Summary

Over 17 years of professional experience as a Senior Software Developer focusing on Spring (Java, backend) and Angular (TypeScript, frontend). Deep hands-on experience in payment, POS systems, and the energy sector. Comfortable working on large enterprise software projects as well as greenfield projects, both solo and in a team. High standards for code quality and experienced in test automation, test-driven development, agile methods, software architecture, and customer communication.

Languages

German

Native

English

Advanced

French

Elementary

Education

Oct 2013 - Oct 2015