Full Stack Kotlin/Java Developer (m/f/d) - in the Cologne Startup

Do you want to be more than a byte in the data sea? Would you like to take on responsibility in agile teams with passion and actively contribute to driving the climate transition with us? Then we should definitely get to know each other!

This is us

As an agile, green startup and specialist for energy management and visualization software, we actively participate in shaping a sustainable, climate-neutral future. Our mission is to make energy consumption management so simple with intuitive, AI-driven software that it becomes a matter of course for everyone – whether companies or private households – and effectively enables energy providers and corporate customers to reduce both energy consumption and their CO2 footprint. With our approximately 35 talented colleagues, we are making the digitalization of the energy industry a real opportunity.
Since 2025, we have been part of the Hausheld group: Together with Hausheld AG, Solandeo GmbH, and Mako365 GmbH, we form the first full-service platform for smart metering in Germany.

Our Stack:

• Kotlin, Spring, Java
• TypeScript, React, Redux, Recoil
• Jest, React Testing Library, Gauge & Taiko
• REST, OpenAPI
• SASS, CSS Modules
• Python, Pandas, NumPy

Our Tools:

• IntelliJ IDEA, VS Code
• git, Maven, webpack
• GitOps, Gitlab CI, Argo CD
• PostgreSQL & TimescaleDB, MariaDB
• Jupyter Notebook
• Kubernetes, Helm, Kafka, Docker

Your Role

As part of a motivated and innovative team, you will take care of the future of sustainable energy management. An excellent and sustainable product begins with a clear idea and vision. As a software developer, you will be involved in all steps of your product's lifecycle and will work with our product management and architects on the product development strategy. A high standard, precision, and critical questioning start for you even before coding.

Tasks

• Together with the developer team, the product owners, and the UX/UI designers, you will drive the further development of our SaaS solutions (especially interfaces).
• You will design, test, maintain, and continuously improve the software, both independently and within your team.
• You will provide technical advice to product management and discuss technical and functional requirements and their implementation with them and the business department.
• In the DevOps area, you will increasingly take on co-responsibility for architecture, programming, and testing.
• Through pair programming, code reviews, and prototyping, you will continuously develop not only our products but also yourself.
• You will regularly exchange ideas with our agile and interdisciplinary teams within the framework of "DevComs" or our Architecture Board.
• You will look beyond your own nose, realize your ideas in monthly GreenDays, and have the opportunity to contribute these ideas to product development.

Qualification

• You have successfully completed your studies in IT or have a comparable qualification that can impress us.
• Furthermore, you already have initial experience as a software developer, ideally in a SaaS environment.
• You have initial practical experience with microservices and cloud infrastructures.
• You excel with extensive Java or Kotlin knowledge, ideally in a Spring context. Alternatively, you score with very good JavaScript/TypeScript know-how and have experience with common frameworks.
• You are familiar with the use of standard tools, especially in an agile environment, such as JIRA and Confluence, for controlling and documenting development.
• As a creative, analytically thinking mind, you enjoy new technologies and have a good sense of quality.
• You live the startup mentality, are motivated, and like to tackle things directly.
• You have good German and very good English language skills.

Benefits

• Intensive coaching and further training opportunities, as well as participation in DevCom and the Architecture Board.
• A permanent employment contract with the opportunity to help shape the green startup scene.
• Startup atmosphere and plenty of scope for design, flat hierarchies, and short distances.
• Flexible working hours and, of course, the option to work from home.
• Take Your GreenDay! Leave everyday life behind and dedicate one day a month entirely to your own ideas.
• Regular team events (bouldering, board and online game evenings, etc.) and daily foosball tournaments with ambitious colleagues aka foosball pros.
• An office full of sprint memes and daily songs (e.g., Friday always ends with the playlist "Good Vibes").
• Inexhaustible coffee and water supplies, as well as regularly fresh fruit.
• Culturally, sportingly, and transport-wise very well-connected location.

If the challenge of joining us on our mission excites you, simply send us your CV and cover letter via the form.