Principal Software Engineer (m/f/d)

At 1KOMMA5°, we pursue a clear vision: Living on wind and sunlight forever for free. To make this a reality, we are building the energy system of the future with Heartbeat AI. Want to be part of it?
We bring together regional craftsmanship and scalable software: We don't think of solar, batteries, heat pumps, and e-mobility as isolated components, but control them as an intelligent, integrated overall system in our virtual power plant. Directly connected to the electricity market – in real time, fully automated. This way, energy is used when it is available from renewables and particularly cost-effective. By 2030, our goal is to transition 1.5 million households to renewable energies. Over 3,000 people are working towards this every day, at more than 80 locations worldwide, from Finland to Australia.

Learn about our Product & Tech team!

• Shape the organisation's technical strategy and innovation efforts
• Accountable for consistent execution of technical decisions by setting clear direction and holding teams accountable for implementation
• Ensure continuously that our software architecture is shaped in close alignment with product management to support current and future product direction
• Lead architectural direction to enable the delivery of scalable, maintainable, and state-of-the-art solutions
• Translate business requirements into technical solutions
• Tackle and resolve deep technical challenges with urgency and precision
• Mentor and challenge engineers to accelerate their professional growth
• Build and scale a high-performance tech organisation and engineering culture
• Embed security and reliability as direct customer value
• Architect our systems and APIs so AI agents operate as first-class users with machine-readable contracts and structured errors that let agents self-correct
• Drive the org's transformation to agentic engineering, reshaping how teams work so agents execute safely while humans stay accountable

• AI-assisted development with Cursor and agentic coding workflows
• Cloud & Infra: Google Cloud Platform, GKE (Kubernetes), Cloud Run, Terraform/IaC, Vercel
• Messaging & IoT: Eclipse Hono, MQTT, Mender
• Data & BI: PostgreSQL, BigQuery, SQLMesh, Looker
• Observability: Datadog, OpenTelemetry
• Languages: TypeScript (Nest.js), Java, Go, Flutter, Ruby on Rails
• DevOps: CI/CD pipelines (GitHub Actions)
• Linear, Notion, Figma, Miro

• Extensive hands-on experience in software development with multiple general-purpose programming languages for a minimum of 5 years
• A proven track record of architecting scalable and secure systems, demonstrating a strong commitment to quality
• Extensive experience in designing and implementing APIs that enable seamless integration and system communication
• An agile and result-oriented mindset, with a strong emphasis on collaboration and teamwork
• Experience communicating with stakeholders in business terms and understanding the technical implications of their requirements
• Industry-leading experience driving cross-functional teams and enforcing engineering alignment in fast-paced environments, including making and following through on critical technical decisions
• Experience designing systems and APIs for agent consumption, with structured errors and clear contracts that let agents self-correct
• Capability to guide an engineering team through the shift to agentic engineering, reshaping workflows so agents execute safely while humans stay accountable for every outcome
• Strong verbal and written communication skills in English, with proficiency in German considered a plus