Senior Full Stack Software Engineer (Java/Kotlin)

CoreWillSoft GmbH is a German-based company working on secure IoT software solutions and services. The mission of CoreWillSoft is to help businesses protect their assets, employees, and data by providing advanced software solutions and services in the security industry.

We are looking for a backend-oriented Senior Full Stack Engineer to join the development of a security-critical locking management platform. The role is approximately 70% backend development with Java/Kotlin and 30% frontend or mobile development. Strong commercial backend experience is therefore essential for this position.

You will work on products used by businesses across Western Europe, USA and Canada.

Our team operates in a scaled agile approach across Europe with a headquarter in Bonn, Germany. It is responsible for the complete software development lifecycle; including ideation, implementation, and operation of the secure IoT software operating smart buildings and smart homes across the world.

Join us to work on cool and innovative projects involving high-security hardware in a nice international and creative environment that allows you to learn and advance.

Your Skills:

Backend:

• 5+ years of experience with Java and/or Kotlin;

• Solid experience with Spring Boot; Spring Security;

• Experience designing and building microservices architectures;

• Experience with RESTful APIs;

• Knowledge of scalability, performance optimization, and high-load systems;

• Experience with Docker and containerized applications;

• Familiarity with cloud platforms (AWS, Azure, or GCP);

• Experience with CI/CD pipelines (GitHub Actions, GitLab CI, etc.);

• Experience with relational and NoSQL databases (e.g., PostgreSQL, MongoDB);

• Understanding of secure coding practices and backend security principles;

• Familiarity with monitoring and observability tools (Prometheus, Grafana, ELK).

   

Frontend:

• Experience with React, Angular, or Vue.js;

• Understanding of modern frontend development practices;

• Ability to build and integrate UI with backend services;

AI & Modern Development:

• Hands-on experience using AI tools in development workflows (e.g., Claude, GitHub Copilot).

• Experience applying AI for:

  • code generation and refactoring;

  • debugging and optimization;

  • solution design and problem-solving;

• Understanding of how to effectively integrate AI into daily engineering workflows.

What You’ll Do:

• Design, develop, and maintain scalable backend services using Java/Kotlin and Spring Boot;

• Contribute to frontend development using React, Angular, or Vue.js;

• Actively use AI tools (e.g., Claude, Copilot, ChatGPT) to improve development efficiency, code quality, and solution design;

• Participate in architectural decisions and contribute to system design;

• Collaborate closely with product and business stakeholders to deliver impactful solutions;

• Take ownership of features from concept to production;

• Ensure performance, scalability, and security of applications;

• Work with cloud infrastructure and modern DevOps practices.

• Experience with Kotlin Multiplatform or Android development;

• Knowledge of cryptography and security systems;

• Experience in IoT, SaaS, FinTech, or high-load systems.