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

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 such as Aramark, Consortium Gastronomie, Feinkost Käfer, TSG Hoffenheim, and VfB Stuttgart. Full support from requirements analysis through implementation and support.
Successfully conceived and developed the NDS SmartPOS platform ("Runner App"): - Designed the software architecture and implemented according to Modern Android Development principles. - Led a small development team (1 Android expert, 1 working student) with 50% in-house 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, demonstrably increasing sales staff efficiency.
Independently developed and implemented critical infrastructure components: - Reporting server (SQL, JasperReports): Proven reduction of accounting effort by eliminating daily manual transfers into the ERP system. - ZVT plugin: Solely responsible for implementing the serial protocol with Java/Netty over TCP/IP. - Cost savings of several thousand euros per site for clients by replacing proprietary solutions (via the ZVT plugin). - In productive use at multiple Bundesliga stadiums with high transaction volumes per match day (ZVT plugin).
Fully in-house development of specialized plugins and server applications to extend SAP Customer Checkout functionality: - Waiter teams plugin: Enables teams of waiters to work and settle their accounts collectively. - SQL reporting: Conceptualized and fully documented solo. - RFID payment solution for employee cards: Responsible for the entire development cycle. - Integration with reservation services: Designed and co-implemented seamless connections to Luca and other services with a colleague.
On-site technical support directly at client sites, including: - Rapid troubleshooting in real-time, high-volume transaction environments. - Direct coordination with stakeholders for continuous system improvements based on practical experience.
Tools & 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, Message Queuing, MQTT, RabbitMQ, Apache Camel, Apache CXF, Apache FOP, Apache PDFBox, Swagger, OpenAPI (OpenAPI Specification), 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 Database, Apache Derby, Microsoft SQL Server, Microsoft SQL Server Reporting Services (SSRS), JasperReports, Linux, Microsoft Windows Server, Hetzner Cloud, AWS, S3 Object Storage, SAP Customer Checkout, POS systems, ERP, Payment SDKs, Dallmayr Pay, ZVT, ACI e.Socket, RFID, Mifare, Netty, jSerialComm, OAuth2, OpenID Connect (OIDC, 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 SAP Customer Checkout implementation, including requirements analysis, solution design, and best practices for customer success.
Independently conceived and developed critical payment solutions: - Full architecture and implementation of terminal integrations for Clover, GlobalPay US/UK, and ACI Payments. - Self-driven development from prototype to production-ready solution, including extensive component testing. - Delivery of fully documented and tested solutions to clients for final approval with payment providers.
Successfully developed bespoke enterprise solutions: - SQL reporting with automated (S)FTP upload: Independently designed the data architecture and implemented the complete workflow. - VIP customer management: Developed a specialized plugin for automatic VIP discount and credit assignment in retail and food & beverage environments. - End-to-end responsibility for all projects from requirements analysis through architecture, programming, delivery, and support.
Tools & 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, End-to-end (E2E) Testing, Protractor, Playwright, Mockito, REST, SOAP, OData, WebSockets, MQTT, RabbitMQ, Apache Camel, Apache CXF, Swagger, OpenAPI (OpenAPI Specification), JSON, XML, XSL, Nginx, Nginx Reverse Proxy, Docker, Docker Compose, Git, GitHub, Bitbucket, Jenkins, SonarQube, DevOps, Snyk, OWASP Dependency-Check, DevSecOps, PostgreSQL, Microsoft SQL Server, SAP HANA Database, Apache Derby, JasperReports, Linux, Microsoft Windows Server, SAP Customer Checkout, POS systems, ERP, Payment SDKs, OAuth2, OpenID Connect (OIDC), 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 (pagination, additional views). - Significantly increased test coverage in the Spring Boot backend. - Rapid onboarding and efficient execution according to given requirements and standards.
Tools & technologies: Java, JavaScript, TypeScript, HTML5, CSS, SQL, Shell, Spring Boot, Spring Framework, Spring Security, Angular, RxJS, NgRx, Hibernate, Unit Testing, JUnit, Jasmine, Jest, Karma, End-to-end (E2E) Testing, Protractor, Playwright, Cypress, Mockito, REST, Swagger, OpenAPI (OpenAPI Specification), JSON, Docker, Git, GitHub, Jenkins, DevOps, DevSecOps, Microservices, PostgreSQL, Linux, Microsoft Windows Server, OAuth2, OpenID Connect (OIDC), 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 implementation leadership for SAP Customer Checkout, with full understanding of business requirements and technical possibilities.
Fully responsible development of mission-critical plugins and server applications: - Plugin for accelerated day-end closing: Reduced closing time by approx. 70%, providing significant operational advantages at large events. - Pioneered the Waiter Teams plugin: Independently conceived and implemented for the first deployment at Oktoberfest. - SQL-based reporting system: Complete architecture and implementation of a custom reporting framework.
On-site technical support at client locations, including: - Rapid troubleshooting in real-time, high-transaction environments. - Direct coordination with stakeholders for continuous system improvements based on practical experience.
End-to-end responsibility for the entire development cycle from initial concept through architecture, programming, testing, documentation, and maintenance.
Tools & 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, End-to-end (E2E) Testing, Protractor, Playwright, Mockito, Dagger, Hilt, Retrofit, Room, REST, SOAP, WebSockets, MQTT, RabbitMQ, Apache Camel, Apache CXF, Swagger, OpenAPI (OpenAPI Specification), 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 Database, Apache Derby, Microsoft SQL Server Reporting Services (SSRS), JasperReports, Linux, Microsoft 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 (OIDC), JWT, Auth0, Maven, Gradle, IntelliJ, UML, Agile, Scrum, CI/CD, TDD, Linux, Jira, Confluence, Asana, Microsoft Office

Jan 2020 - Mar 2021

3 months

Mainz, Germany

Freelance Senior Full Stack Developer

C24 Bank GmbH

Interim support as part of a task force on the website and web app, especially integrating animations, adjusting content and styling, and extending web app functionality.
Tools & technologies: JavaScript, TypeScript, HTML5, CSS, Angular, RxJS, NgRx, Scully, Unit Testing, Jasmine, Jest, Karma, End-to-end (E2E) Testing, Protractor, Playwright, Cypress, Selenium, REST, Swagger, OpenAPI (OpenAPI Specification), 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 conceptualization and implementation of a web application prototype for interactive presentation of current construction projects.
Tools & 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 in UI development of the CCO customer display.
Tools & 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 SAP Customer Checkout POS system: - Implemented complex feature extensions for the new frontend (NGUI) based on Angular and SAPUI5. - Co-responsible for developing interfaces to integrate third-party systems, significantly enhancing the product's market relevance and flexibility. - Actively participated in architectural decisions and successfully implemented jointly developed concepts.
Contributed to product quality and stability: - Conducted code reviews to ensure code quality and adherence to corporate standards. - Actively participated in agile development processes including sprint planning, daily scrums, and retrospectives. - Continuously integrated development results into the existing codebase following CI/CD principles.
Additional responsibilities: - Effective collaboration in an internationally distributed development team. - Documentation of implementations and architectures for sustainable knowledge transfer within the company. - From 2021, supported the team part-time.
Tools & technologies: Java, JavaScript, TypeScript, HTML5, CSS, SQL, Shell, Spring Framework, Spring Security, Angular, RxJS, NgRx, SAPUI5, UI5, EclipseLink, Unit Testing, JUnit, Mockito, Jasmine, Jest, Karma, End-to-end (E2E) Testing, Protractor, Playwright, Cypress, Selenium, SonarQube, DevSecOps, REST, SOAP, OData, WebSockets, Apache CXF, Swagger, OpenAPI (OpenAPI Specification), JSON, XML, XSL, Apache FOP, Docker, Git, GitHub, Jenkins, DevOps, Microsoft SQL Server, SAP HANA Database, Apache Derby, Linux, Microsoft Windows Server, SAP Customer Checkout, POS systems, ERP, Payment SDKs, Netty, jSerialComm, OAuth2, OpenID Connect (OIDC), 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 at a publicly traded energy provider and technically co-designed and implemented a portal for managing charging stations and electric vehicle fleets based on Angular and the existing backend.
Tools & technologies: JavaScript, TypeScript, HTML5, CSS, SQL, Java, Spring Boot, Spring Framework, Unit Testing, JUnit, Angular, RxJS, NgRx, Angular Material, REST, Jasmine, Jest, Karma, End-to-end (E2E) Testing, Protractor, Selenium, Webpack, OAuth2, OpenID Connect (OIDC), JWT, JSON, MongoDB, NoSQL, Microservices, DevOps, DevSecOps, Microsoft Azure, Azure App Service, Azure API Management, Azure Application Insights, ServiceBus, 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 attendees connect better. Coordinated with clients and external developers, managed app-backend integration, 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. Collaborated closely with backend and frontend developers and QA in a Scrum team, aligning requirements with all stakeholders.
Major contributor to Deep Map™ WebSDK v2+, simplifying indoor map integration for clients. Selected technologies, designed architecture, and reimplemented components using the latest OpenLayers version, TypeScript, and modern frameworks.
Integrated third-party services (SOAP, REST) from client systems in the trade fair environment to synchronize user data between the website and mobile app.
Automated configuration of trade fair web apps, achieving significant time savings. Extensively enhanced the existing Excel parser and nearly fully automated configuration with Jenkins.
Tools & 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, End-to-end (E2E) Testing, Protractor, Selenium, Ionic, Cordova, Retrofit, Room, OpenLayers, JSON, XML, OAuth2, OpenID Connect (OIDC), 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

Internship Phases of Dual Study Program, Software Developer

sobedi GmbH / apinso GmbH

Practical phases of the dual study program. Focus: conceptualizing and implementing requirements in Java and Groovy (backend and frontend). Followed by full-time position as Software Developer at apinso GmbH.
Implemented a domain-specific language based on Groovy that allows the use of Excel-like formulas.
Developed a tool for automatic comparison of application databases to ensure successful data migration.
Automated application deployments using Apache Ant.
Tools & 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 practical 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 teams. High standards for code quality and experienced in test automation, test-driven development, agile methodologies, software architecture, and client communication.