Java entwickler Jobs in Rüsselsheim

Your mission

We are looking for a Fullstack Engineer whose primary strength lies in backend engineering, but who is also comfortable implementing production-ready frontend features.
Most of your technical depth will be applied on the backend, but feature ownership does not stop at the API boundary. You join a small cross-functional product team that works with a Product Owner who sets the why, what and when, while the team owns the how. Our technology stack is a containerized PHP/Symfony microservices backend running on AWS infrastructure managed through Terraform, and an Angular frontend. We practise continuous delivery, so your work reaches production quickly and is covered by automated end-to-end tests.

Your profile

You will

• Own features end-to-end, from architecture, data model and backend implementation to frontend, deployment and production support
• Design, build and operate container-based backend services, APIs and infrastructure in AWS
• Design solutions for distributed, message-driven and service-oriented systems
• Implement the frontend part of your features in Angular based on product requirements and designs
• Analyse business requirements and translate them into pragmatic technical solutions, and continuously improve the performance, reliability and maintainability of existing applications
• Write clean, maintainable and understandable code with appropriate automated tests; conduct thorough code reviews and contribute to engineering standards
• Troubleshoot and debug issues across backend, frontend and infrastructure
• Collaborate closely with product, design and other engineers in an agile environment
• Use AI coding assistants and agents as a regular part of your engineering workflow: break engineering work down so that it can be delegated effectively to AI agents, and critically review AI-generated code with the same standards as human-written code

You have

• 5+ years of professional software development experience, with the majority of your experience focused on backend engineering
• Strong professional experience with PHP and Symfony or with another backend ecosystem such as Java, Python or Node.js and the willingness to work in PHP/Symfony from day one
• In-depth understanding of REST APIs, message-based systems, microservice architectures and distributed systems
• Strong experience with relational databases, data modeling and schema design
• Hands-on professional experience implementing frontend features in Angular or a comparable framework such as React or Vue.js; strong in component and state logic and API integration; solid enough in styling to implement a given design.
• Experience with automated testing, Docker and containerized applications, and cloud-native development, ideally hands-on with AWS
• Experience using AI coding assistants or agents such as Claude Code, Cursor, or GitHub Copilot
• Clear communication in English, our working language, and a collaborative engineering mindset; German is a plus

Bonus points for

• Experience with NoSQL systems
• CI/CD pipeline design, Infrastructure as Code (Terraform or CloudFormation) and serverless architectures
• Domain-Driven Design
• LLM-based application development, including RAG, tool/function calling, MCP servers, or agent orchestration
• Component libraries, design systems, and frontend performance optimization
• AWS certifications

Why us?

• Inclusive, multinational team with 18+ nationalities. English is our company language
• Remote-first within Germany; hybrid-friendly with a modern office in Mainz (open spaces, coffee bar, meeting pods)
• Flexible working hours. We trust you to deliver results, wherever and whenever you work
• Low-hierarchy, open-feedback culture where your voice shapes strategy
• Radical transparency: smart minds collide, great ideas happen
• Real ownership: you ship features end-to-end and see them in production
• AI coding tools as a standard part of the engineering workflow
• Fully paid company workation every year
• Learning & development budget: conferences, certifications, and language courses
• 50 € hrmony voucher: sports, takeout, shopping, your call
• Hardware of your choice
• Competitive salary plus performance-based bonus
• Direct impact on the circular battery ecosystem, helping close the loop on used EV batteries

About Us

At Circunomics, we are building the B2B marketplace and data platform for the battery lifecycle: trading first-life, surplus, and second-life batteries, battery analytics, and the digital battery passport. As a green technology and sustainability startup, we use modern software and data-driven insights to keep batteries in use longer, minimize waste, and help accelerate the transition to a sustainable energy future.