Harold T.-Senior Software Developer | OOP . Full Stack . Web & Mobile . Cloud-Native
Check rate
Experience
CPU Watcher — Cloud-Native Monitoring Application
SEUYTEL
- Planned and developed a CPU monitoring application for monitoring system performance and resource utilization.
- Designed and implemented a Spring Boot backend providing a REST API for processing and exposing monitoring data.
- Developed the React frontend for presenting monitoring information in a clear and user-friendly interface.
- Integrated PostgreSQL for persistent storage and management of application data.
- Containerized the application and its services using Docker Compose.
- Automated infrastructure provisioning and deployment using Terraform on AWS.
- Structured the application as a modern, maintainable system using REST-based communication between frontend and backend.
- Designed and developed a secure, scalable CPU monitoring architecture (cpu-watcher) with a dedicated collector application that streams monitoring data to the backend, reducing direct exposure of system resources.
- Designed a secure cloud infrastructure with the database isolated within a private network and OIDC-based authentication.
- Implemented Infrastructure as Code with Terraform and integrated version-controlled CI/CD pipelines to automate testing, infrastructure changes, and application deployments.
- Designed and implemented the frontend delivery architecture using AWS CloudFront.
Stack: Spring Boot · React · PostgreSQL · REST API · Docker Compose · Terraform · AWS
Main Events — Mobile & Web Platform
SEUYTEL
- Contributed to the development and release of a mobile application using React Native.
- Contributed to the development and maintenance of associated React.js web applications.
- Integrated frontend and mobile components with backend services through REST APIs.
- Contributed to the development and integration of Laravel-based backend services.
- Configured and maintained the Ubuntu-based server environment supporting the applications.
- Worked with PostgreSQL for application data management.
- Used Git-based version control and CI/CD processes to support development and deployment workflows.
- Supported the technical delivery of the applications from development through to production release.
Stack: React Native · React.js · Laravel · REST API · PostgreSQL · Ubuntu · Server Administration · Git · CI/CD
Co-Founder / Software Developer
SEUYTEL
- Contributed to the design, development, and release of Main Events, a mobile application and associated websites.
- Contributed to the design, development, and publishing of SEUYTEL React.js websites.
- Configured and administered a GDPR-compliant on-premises cloud infrastructure for SEUYTEL.
- Contributed to the technical and organizational management of the company.
BTB Database — ERP System
Fraunhofer
- Independently planned, designed, and developed a modern ERP system within an enterprise environment.
- Analyzed and documented the existing Microsoft Access system and data structures as the basis for modernization.
- Performed the migration from Microsoft Access to PostgreSQL, including the transfer and adaptation of existing data structures.
- Designed and developed a Laravel-based backend with REST API services.
- Designed and implemented the React-based frontend for the new ERP system.
- Integrated SAP-based authentication / SSO into the application environment.
- Worked within an Ubuntu-based development and server environment and used Git for version control.
- Took independent responsibility for development tasks across the database, backend, frontend, and system integration.
Stack: Laravel · React · PostgreSQL · REST API · SAP · Ubuntu · Git
Software Developer
Fraunhofer IST
- Migrated an existing Microsoft Access database to PostgreSQL, including the transfer and adaptation of existing data structures.
- Designed and developed a backend system using Laravel.
- Designed and developed a React-based frontend.
- Implemented SSO authentication based on a SAP smart card.
- Developed and worked in a controlled corporate environment handling sensitive business and personal data in compliance with applicable data protection and security requirements.
- Independently handled development, documentation, and technical coordination tasks.
IT Technician
Freelancer
- Conducted IT infrastructure projects across two locations of a major retail chain.
- Installed and commissioned wireless access points.
- Verified network connectivity and the proper operation of installed components.
- Independently performed on-site technical work in accordance with defined project requirements.
EstateNews — Native Android Application
SEUYTEL
- Independently planned and developed a native Android application using Kotlin and the MVVM architecture.
- Designed and implemented the application user interface and core functionality.
- Developed a PHP-based backend providing REST API services.
- Integrated the Android application with the backend for data exchange and processing.
- Implemented and managed the MySQL database for persistent application data.
- Used Git for version control and structured software development workflows.
- Took responsibility for the technical implementation across the mobile application, backend, and database components.
Stack: Kotlin · Android · MVVM · PHP · REST API · MySQL · Git
Independent Software Development
EstateNews
- Planned and independently executed a personal software project.
- Designed and independently developed a native Android application using Kotlin.
- Developed a PHP-based REST backend for providing and processing application data.
- Integrated and managed a MySQL database.
- Implemented the MVVM architecture and developed the application's user interface.
- Implemented features including user authentication, radius-based search, Google Maps integration, content filtering, and favorites management.
- Independently managed the project from initial concept through development and technical integration.
First & Second Level Support / IT Support
Wertgarantie
- Provided first- and second-level customer support via phone and email.
- Analyzed and resolved technical inquiries and escalated complex issues to the appropriate departments.
- Contributed to the rollout of newly developed software.
- Performed testing and evaluated the software from an end-user perspective.
- Collected, documented, and systematically communicated customer feedback and improvement suggestions to the development team.
- Worked in a regulated insurance environment, handling personal customer data in accordance with applicable data protection and security requirements.
Data Entry / Data Processing
Wertgarantie
- Entered and maintained contract and customer data in internal systems.
- Processed and reviewed incoming signed contracts.
- Handled personal and confidential customer data carefully within a regulated corporate environment.
Industry experience
See where this freelancer has spent most of their professional time.
Experienced in Information Technology, Insurance, and Retail.
Business area experience
See which departments and functions this freelancer has contributed to most.
Experienced in Information Technology, Product Development, Operations, Project Management, Customer Service, and Quality Assurance.
Summary
Software developer with hands-on experience in building full-stack, backend, and modern enterprise applications as well as mobile applications. Strong knowledge of Java, Kotlin, JavaScript/TypeScript, and PHP, and of frameworks like Spring Boot, Laravel, React, and React Native. Experience in building REST APIs, connecting and migrating databases, as well as containerization, for example with Docker, and implementing CI/CD and IaC solutions. Independent and solution-oriented way of working with experience in delivering technical projects and working across different IT environments.
Skills
- Programming Languages: Java, Kotlin, C++, Python, Javascript, Typescript, Php, Sql
- Backend Entwicklung: Spring Boot · Spring · Laravel · Rest Apis · Hibernate/Jpa · Microservices
- Frontend & Mobile Entwicklung: React · React Native · Android Xml · Html · Css
- Databases: Postgresql · Mysql
- Cloud & Devops: Docker · Kubernetes · Terraform · Aws · Ci/Cd · Docker Compose · Iac · Nginx · Oidc
- Architectures & Design Patterns: Mvc · Mvvm · Microservices · Rest · System Design · Authentication & Authorization
- Networking & Infrastructure: Nat · Gateways · Network Configuration · Access Points · Network Components · Docker Networking · Ssh
- Development Tools: Claude Code · Git · Gradle · Maven · Composer · Android Studio · Vs Code · Eclipse · Jira · Confluence · Pgadmin
- Systems: Ubuntu · Windows
Languages
Education
Technische Universität Braunschweig
Bachelor's Studies · Computer Science · Braunschweig, Germany
Bilinguales Gymnasium Gouache
Abitur · Science
Certifications & licenses
Cloud Practitioner Essentials
AWS
Docker Mastery with Kubernetes and Swarm
Udemy
Full-Stack Web Developer
Udemy
Kotlin Android Developer
Udemy
Statistics
Experience
Global experience
Expertise
Qualifications
Profile
Frequently asked questions
Have questions? Find more information here.
Harold is based in Braunschweig, Germany and can operate in on-site, hybrid, and remote work models.
Harold speaks the following languages: French (Native), German (Advanced), English (Advanced).
Harold has at least 4 years of experience. During this time, Harold has worked in at least 10 different roles and for 6 different companies. The average length of individual experience is 5 months. Note that Harold may not have shared all experience and actually has more experience.
Based on recent experience, Harold would be well-suited for roles such as: CPU Watcher — Cloud-Native Monitoring Application, Main Events — Mobile & Web Platform, Co-Founder / Software Developer.
Harold's most recent position is CPU Watcher — Cloud-Native Monitoring Application at SEUYTEL.
In recent years, Harold has worked for SEUYTEL, Fraunhofer, Fraunhofer IST, Freelancer, and EstateNews.
Harold is most experienced in industries like Information Technology, Insurance, and Retail.
Harold is most experienced in business areas like Information Technology, Product Development, and Operations. Harold also has some experience in Project Management, Customer Service, and Quality Assurance.
Harold holds a Bachelor in Computer Science from Technische Universität Braunschweig.
Harold has 4 certificates. Among them, these include: Cloud Practitioner Essentials, Docker Mastery with Kubernetes and Swarm, and Full-Stack Web Developer.
Harold is immediately available full-time for suitable projects.
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The median daily rate is the middle value of all daily rates — half of comparable freelancers charge less, half charge more. Unlike the average, it is barely affected by outliers.
Calculated based on our freelancers’ daily rates as of 19 Sep 2026. Actual rates may vary depending on seniority level, experience, skill specialization, project complexity, and engagement length.
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