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Ralf SiemonRS

Ralf Siemon

Senior PHP Developer

€800/day
Frielendorf, DE
15+ years

Average response time: 1 hour

Freelancer profile translated to English.
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About Ralf

Web applications in PHP/Symfony – for complex business logic

With over 15 years of PHP experience, I bring in-depth knowledge of modern web development. I also have many years of Java experience from previous projects and am familiar with other languages and technologies. In recent years, I have primarily worked on B2B web applications in the e-commerce environment, including a shop system with over 40 concurrently operated tenant shops and an integrated backend. I have also designed and implemented ETL processes for data warehouse systems multiple times.

Most recently, I have intensively engaged with AI-assisted development (Claude Code) and actively use these tools in my daily work. I see them as a productivity multiplier and a sensible component of modern software development – without relinquishing professional review and architectural responsibility.

I particularly enjoy taking on projects where something structurally new is created or fundamentally rethought – be it a new development, a comprehensive overhaul, or the replacement of established legacy systems. I quickly familiarize myself with existing systems, build clean architectures, and translate functional and technical requirements into working software.

I hold a degree in Mathematics and have been self-employed since 2010.

I am currently looking for projects in PHP/Symfony web development – ideally with a capacity of 2 days per week. Projects related to data integration or data warehousing are also welcome.
  • German

    Native or bilingual

  • English

    Fluent

Remote only
Primarily works remotely

Experience

  • Chronext GmbH
    Software Developer/Consultant
    E-COMMERCE
    December 2021 - October 2024 (2 years and 10 months)
    Consulting/coaching of internal employees and independent development within the scope of the new implementation of a data warehouse system.
    • Python
    • Apache Airflow
    • dbt
    • Amazon Redshift
    • Git
    Data Warehouse Python Airflow Amazon Redshift
  • Adam Riese GmbH
    Software Developer
    BANKING AND INSURANCE
    October 2020 - February 2021 (4 months)
    Architecture and initial introduction of a cloud data warehouse system, including ETL process based on Microsoft Azure. Training of in-house employees in the system.

    • Microsoft Azure Synapse Analytics
    • Microsoft Azure Data Factory
    • Microsoft Azure Functions
    • Microsoft Azure Storage
    • Google Analytics
    • Python
    • Git
    Data Warehouse Python Google Analytics Microsoft Azure
  • Smilegate Games GmbH
    Software Developer
    September 2017 - April 2018 (7 months)
    Reconstruction of the European company website based on SAP hybris in a team. Pixel-perfect implementation of design drafts including animations, with a CMS approach for content maintenance via the hybris backend.
    • Java
    • hybris
    • Spring
    • Eclipse
    • Scrum
    • Jira
    • Git
    Java SAP Hybris Spring Scrum

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Education

  • Degree in Mathematics
    Philipps University Marburg
    2001
    Mathematikstudium mit Nebenfach Informatik. Programmiersprachen: Pascal, C++, Haskell, Fortran.

Skill set

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