Open to opportunities

Martin Grellmann

@martingrellmann

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Senior full-stack engineer specializing in SAP BTP, S/4HANA modernization, and enterprise API integration.

Brazil

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What I'm looking for

I’m looking for a senior engineering role focused on SAP BTP/S/4HANA modernization and enterprise API integration, where maintainability and Clean Core principles matter. I want a collaborative, cross-functional team with clear quality standards and architecture-driven delivery.

I’m a senior software engineer with 20+ years of full-stack delivery experience and a strong recent focus on SAP full-stack engineering across SAP BTP and S/4HANA. I combine long-term reliability with hands-on development, modernization, and architecture-oriented thinking across both SAP and modern web platforms.

My core strengths center on SAP development and extensibility: ABAP/ABAP Objects, CDS Views, OData (v2/v4), RAP, CAP, SAP UI5, and Fiori Elements—paired with SAP BTP integration and enterprise API work. I’m particularly focused on maintainability through Clean Core principles, and on side-by-side/developer extensibility patterns that keep solutions future-ready.

In recent work, I improved backend API interfaces in S/4HANA projects to support integration and system readiness, supported productive services during hypercare, and refactored an undocumented Dynpro application into object-oriented ABAP to strengthen future S/4HANA compatibility. I’ve also delivered UI5/Fiori applications and contributed to ERP-to-S/4HANA migration and MII efforts, ensuring code quality via refactoring, reviews, and architecture documentation.

I bring a strong web engineering foundation as well—JavaScript, TypeScript, React, Node.js, Next.js, PHP, Drupal, and REST APIs—and I’ve modernized legacy platforms with cloud-oriented infrastructure and API-driven, service-oriented designs. I collaborate effectively with business teams and solution managers, and I aim for stable, high-quality outcomes through Scrum-based execution and clear technical communication.

Experience

Work history, roles, and key accomplishments

Current

Technical Lead / IT Specialist

Current

Ferienhausvermittlung Fincaferien

Mar 2025 - Present (1 year 3 months)

Led technical modernization and digital transformation of a multi-site vacation rental platform built on Drupal. Designed cloud infrastructure for scalability, defined an API-driven modernization roadmap, and developed enterprise APIs connecting business services with the Drupal CMS.

Drupal PHP REST APIs Cloud Infrastructure API Integration Web Technologies Automation Digital Transformation

Current

Senior SAP Developer

Current

Intecsoft GmbH & Co

Jan 2025 - Present (1 year 5 months)

Improved backend API interfaces in an S/4HANA project to support integration and system readiness. Refactored an undocumented SAP Business Suite Dynpro application into object-oriented ABAP to improve maintainability and future S/4HANA compatibility in IS-U.

ABAP Objects CDS Views OData SAP BTP REST APIs SAP S 4HANA

SAP Technical Consultant

BA Business Advice GmbH

Feb 2022 - Dec 2024 (2 years 10 months)

Developed and extended SAP applications using ABAP, CDS, OData, and SAP UI5/Fiori Elements. Contributed to ERP-to-S/4HANA migration and MII projects and refactored applications for maintainability and clean architecture, including RAP/CAP initiatives on SAP BTP.

SAP ABAP CDS Views OData SAP UI5 FIORI RAPS SAP BTP S 4HANA Public Cloud JavaScript

Software Developer & Linux Admin

Sengicon GmbH

Feb 2021 - Jan 2022 (11 months)

Built and modernized full-stack applications in an Industry 4.0 environment using React frontends and PHP REST backends. Converted legacy PHP to REST APIs, integrated React UIs, and administered Linux LAMP environments while modeling databases and running automated tests.

React JavaScript PHP API Integration PHPUnit Jest MySQL MariaDB PostgreSQL Linux Administration

Webmaster / Web Developer

Ferienhaus-Vermittlung Fincaferien.de GmbH

Apr 2004 - Dec 2019 (15 years 8 months)

Owned web development, operations, optimization, and technical infrastructure for long-running websites and web applications. Developed and maintained PHP/Drupal sites, customized Drupal modules, improved SEO and performance, and enhanced usability to reduce bounce rate.

PHP Drupal HTML CSS Git Jira Linux SAMBA SEO SEA Usability

Education

Degrees, certifications, and relevant coursework

Software Academy by intecsoft

Software Architect (training), Software Architecture

2025 - 2026

Activities and societies: iSAQB CPSA-F Foundation Level; exam planned for Q4/2026.

Completed Software Architect training at Software Academy by intecsoft in Dresden (06/2025–06/2026), covering iSAQB CPSA-F Foundation Level with an exam planned for Q4/2026.

Indisoft GmbH

Full-Stack Web Developer (training), Full-Stack Web Development

2020 - 2021

Completed Full-Stack Web Developer training at Indisoft GmbH in Leipzig (2020–2021).

Indisoft GmbH

Professional Scrum Master I (PSMI), Agile Project Management

2020 - 2020

Completed Agile Project Management training at Indisoft GmbH in Leipzig (05/2020–06/2020) and obtained Scrum.org Professional Scrum Master I (PSMI) certification.