Henning K.

Ruby on Rails Developer

Darmstadt, Germany

Experience

May 2025 - Oct 2025
6 months

Ruby on Rails Developer

evopark GmbH

  • Spearheaded the development and maintenance of multiple Ruby on Rails applications, ensuring high availability and performance for time-critical and performance-sensitive systems in the mobility services sector.
  • Analyzed, debugged, and resolved complex application issues, improving system reliability and reducing downtime by implementing robust bug-fixing and code optimization practices.
  • Enhanced testing frameworks using RSpec and integrated continuous integration pipelines via CircleCI and Docker, achieving faster deployments and higher code coverage.
Aug 2024 - Aug 2024
1 month

Software Developer, System Analysis

Freelancing

  • Developed and deployed a custom export tool integrating WordPress/WooCommerce data into fulfillment partner-compatible formats, streamlining order processing for a publishing and eCommerce client.
  • Conducted comprehensive database analysis on MySQL/MariaDB structures to identify key data relationships and optimize data extraction workflows, improving export accuracy and efficiency.
  • Designed automated data transformation scripts using PHP and Python, reducing manual processing time and ensuring seamless, error-free CSV generation for external fulfillment systems.
Jul 2024 - Jul 2024
1 month

Server Administrator, Web Master, Software Developer

Freelancing

  • Provided rapid emergency response to recover critical systems after a server hardware crash, restoring data integrity and application functionality under tight deadlines.
  • Executed full data and structure recovery from backups and manually reconstructed missing components, achieving 100% restoration of client operations with minimal downtime.
  • Extended and optimized a custom Ruby-based API (Grape framework) to enhance system interoperability and performance across integrated platforms.
Jul 2024 - Jul 2024
1 month

Website Portfolio Consolidation Support

Freelancing

  • Led the consolidation and reorganization of 70+ websites, streamlining hosting environments and improving operational efficiency across a large publishing portfolio.
  • Conducted comprehensive analysis and root-cause diagnostics, identifying and resolving critical performance, security, and configuration issues across multiple CMS platforms.
  • Executed targeted upgrades and migrations to ensure all websites met modern security, compatibility, and scalability standards.
Apr 2024 - Jun 2024
3 months

Data Manager

Freelancing

  • Oversaw the secure handling and processing of 10,000+ records containing personally identifiable and security-related data for an international sports event.
  • Implemented and maintained strict data protection protocols, ensuring compliance with global privacy and security standards.
  • Utilized advanced data analysis tools such as MS Excel, Office 365, and R to validate, organize, and interpret large datasets for operational efficiency.
Apr 2022 - Jun 2022
3 months

Software Developer

Freelancing

  • Redesigned and partially re-implemented a complex order processing and tracking system, enhancing performance, scalability, and maintainability.
  • Modernized legacy infrastructure by migrating to an updated software stack using Ruby, Ruby on Rails, PostgreSQL, and Bootstrap.
  • Optimized database structures and query performance, improving order tracking speed and data accuracy across workflows.
Jan 2022 - Dec 2022
1 year

Software Developer, Server Administrator, System Integrator

Freelancing

  • Modernized and partially re-implemented an enterprise mailing list system, improving reliability, performance, and integration capabilities.
  • Developed a custom API using Ruby and Grape to seamlessly connect multiple websites with the Sympa-based mailing infrastructure.
  • Optimized backend operations on Ubuntu Linux and Postfix, enhancing mail delivery efficiency and reducing system latency.
Jan 2013 - Dec 2021
9 years

Server Administrator, Web Master, Software Developer

Freelancing

  • Administered and maintained a cluster of 20+ virtual servers and containers, ensuring optimal uptime, stability, and performance across all environments.
  • Diagnosed and resolved system-level and application-level issues, improving overall cluster reliability and minimizing downtime.
  • Configured, customized, and optimized software running within Proxmox VE and OpenVZ environments to meet specific client requirements.
Jan 2010 - Dec 2015
6 years

Web Developer, Web Master, Server Administrator

Freelancing

  • Planned, developed, and deployed a custom content management system (CMS) to support a multinational annual PR event, streamlining content creation and publication workflows.
  • Translated complex stakeholder requirements into scalable CMS functionalities, ensuring alignment with business objectives and event timelines.
  • Implemented advanced features such as geo-searching and dynamic content management using Ruby on Rails, MySQL, JavaScript, and CoffeeScript.

Summary

Results-driven Software Developer with over a decade of experience delivering high-quality, scalable web applications and backend systems across diverse industries. Skilled in both Ruby on Rails and PHP/LAMP stack development, with proven success in building, modernizing, and integrating complex digital solutions. Adept at system analysis, API development, and data management, with a strong foundation in database architecture using PostgreSQL, MySQL, and MariaDB. Known for combining analytical precision with hands-on coding expertise, ensuring reliable, efficient, and secure software delivery. Experienced in managing full development lifecycles from requirement analysis and system design to testing, debugging, and deployment while continuously adapting to emerging technologies.

Languages

German
Native
English
Advanced
French
Elementary

Education

Heidelberg University

Diploma in Biology, Ecology · Natural Sciences · Heidelberg, Germany

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