Timon Ringwald
embedded linux, Java, Backend, BSI Standards
Experience
Administrator
Various clients
- Setup and maintenance of multiple web servers.
- Configuration of load balancing to distribute traffic across several servers.
- Implementation of HTTPS with Let's Encrypt certificates for secure data transfer.
- Setup of automated backups and recovery strategies.
- Optimization of server performance through caching (e.g., Redis, Memcached).
- Security measures like SSH hardening, fail2ban, and regular security audits.
- Tools: Nginx / Caddy as web and proxy servers, Docker for containerizing applications, monitoring with Grafana.
Administrator
Various clients
- Setup of a wired and a Wi-Fi network based on TP-Link Omada.
- Planning and implementation of a redundant network architecture to ensure high availability.
- Setup of a Wi-Fi mesh network for seamless roaming between WLAN repeaters.
- Configuration of VLANs to separate different network segments (e.g., employees, guests, IoT devices).
- Implementation of QoS rules to prioritize critical applications (e.g., VoIP, video conferencing).
- Tools: Raspberry Pi with Ubuntu Server, TP-Link Omada controller interface, router, Wi-Fi devices, VLAN configuration via CLI/WEB interface, Wireshark for network analysis.
Backend Developer – Data Exchange Platform
Insurance group
Generation of KVNR: service for creating and securely storing health insurance numbers for insurance clients.
Development of a RESTful API for creating and managing KVNRs.
Implementation of secure storage and transmission of KVNR data in compliance with data protection regulations (e.g., GDPR).
Implementation of efficient validation and error handling to ensure the correctness of generated numbers.
Integration of a logging mechanism for tracking system operations and ensuring auditability.
Creation of an integration service: integrating various internal and external services into a unified data layer for data consumption and processing.
Design and implementation of a microservice architecture for integrating various data sources.
Development of an API gateway solution with Spring Boot to manage communication between internal and external services.
Implementation of mechanisms for synchronizing and harmonizing data from different systems to enable consistent data representation.
Creation of an error handling and retry system to increase the integration service's reliability.
Implementation of a deletion concept for personal data in compliance with data protection regulations (e.g., GDPR).
Tools: Java + Spring Boot, Maven, IntelliJ, Postman, OpenAPI/Swagger, PostgreSQL, OPNsense.
Administrator
Various clients
- Setup of a smart home.
- Integration of various devices (e.g., lighting, heating, security systems) into a resilient Zigbee mesh network.
- Implementation of automation rules (e.g., turn on lights when motion is detected, adjust heating based on weather data).
- Ensuring data integrity and security through encrypted communication between devices.
- Optimized energy consumption analysis and control through intelligent device integration.
- Tools: Linux Raspberry Pi OS, Raspberry Pi as local server infrastructure, Home Assistant as central platform, Zigbee for wireless device communication, MQTT broker for seamless mesh communication.
Pen Tester Training
- Planning and Scoping
- Information Gathering and Vulnerability Identification
- Attacks and Exploits
- Reporting and Communication
- Tools and Code Analysis
Backend Developer – Event Software
Software solution for accrediting meeting participants
- Definition of interfaces and documentation using Swagger/OpenAPI for an API-first approach.
- Designing the backend architecture and implementing it.
- Testing and deploying the solution in the cloud.
- Tools: Java/Spring Boot (Microservices), Swagger, MinIO, MariaDB, GitHub including build pipelines, Kubernetes.
Backend Developer – Whistleblower Protection Software
lettly.de
- SaaS development for various end customers.
- Implementation of cryptographic procedures, including BSI standard TR 02102-1.
- Implementation of security and access concepts in backend systems.
- Setting up a reporting office according to the Whistleblower Protection Act (HinSchG).
- Integration of Stripe as a payment provider.
- Tools: Java/Spring Boot (Microservices), Swagger, MongoDB, MinIO, MariaDB, GitHub including build pipelines, Kubernetes, Linux.
Backend Developer – Voting Software
ballotly.de
- SaaS development for various end customers.
- Implementation of cryptographic procedures, including BSI standard TR 02102-1 and Common Criteria (CC).
- Implementation of the business logic according to election regulations.
- Creating a synchronization concept for a distributed architecture.
- Tools: Java/Spring Boot (Microservices), Swagger/OpenAPI, Redis, SSE, DDA, MinIO, MariaDB, GitHub including build pipelines, Kubernetes, Linux.
Part-time Project
Automotive Supplier
- Creating labels for shipping. Charge labels are printed on an industrial printer, including labels for secondary packaging.
- Designing a server-client software architecture for scalability across multiple workstations.
- Developing interfaces for controlling industrial Zebra label printers.
- Designing and implementing bidirectional data synchronization between the label system and the MS SQL database.
- Support and maintenance of the software.
- Tools: IntelliJ, Java + JavaFX, MS SQL, Linux Raspberry Pi OS, Raspberry Pi.
Fullstack Developer – Plant Monitoring
Mechanical and Plant Engineering
- Further development of the new platform to support production in a distributed machine landscape.
- Development and deployment of solutions according to machine generations.
- Technology consulting for new equipment.
- Tools: Software architecture (EDA, DDD), Java/Spring Boot, MinIO, MySQL, MongoDB, MQTT, Mail proxy & bridges, C#.
Backend Developer - Documentation Tool
In-house development / various clients
- Service app as a documentation and reference tool for machines, projects, real estate & facility management.
- Template-based process documentation for consistent quality.
- Tools: Java/Spring Boot (microservices), NodeJS, MongoDB, MinIO, MariaDB, GitLab, Docker & Docker Compose on Linux servers.
App Developer - Quality Assurance
Road construction and maintenance
- Connected app for quality control in road and asphalt construction.
- Designed and implemented the infrastructure and Android app.
- Mathematical modeling of the business logic.
- Tools: Java, Android, BLE, SQLite, GitLab, Confluence.
Fullstack Developer - Process Management
Agriculture and Forestry
- Further development of an in-house platform for process optimization and management in agricultural businesses.
- Technology consulting.
- Tools: Software architecture (EDA; DDD), Java 8, Angular, NodeJS, Apache Cassandra, MariaDB.
Vocational training in application development
b.i.b. International College Bielefeld
Focus on fullstack and app development
Summary
Added value through digitalization and software development - from the initial idea to the finished solution. "I enjoy working with my clients to find the right solutions!" On the web, I'm at home in the backend - interfaces are my strength.
Languages
Education
B.I.B. International College Bielefeld
Vocational training in application development with a focus on full-stack and app development · Application Development · Bielefeld, Germany
Certifications & licenses
Pen-Tester
Similar Freelancers
Discover other experts with similar qualifications and experience
- English
- Deutsch
2025 © FRATCH.IO GmbH. All rights reserved.