Principal Software Engineer (m/f/d)

1KOMMA5At 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.Want to take responsibility and build solutions that truly matter? Apply now and help us shape the energy world of tomorrow.Learn more about our Product & Tech team!Your missionShape the organisation's technical strategy and innovation effortsAccountable for consistent execution of technical decisions by setting clear direction and holding teams accountable for implementationEnsure continuously that our software architecture is shaped in close alignment with product management to support current and future product directionLead architectural direction to enable the delivery of scalable, maintainable, and state-of-the-art solutionsTranslate business requirements into technical solutionsTackle and resolve deep technical challenges with urgency and precisionMentor and challenge engineers to accelerate their professional growthBuild and scale a high-performance tech organisation and engineering cultureEmbed security and reliability as direct customer valueArchitect our systems and APIs so AI agents operate as first-class users with machine-readable contracts and structured errors that let agents self-correctDrive the org's transformation to agentic engineering, reshaping how teams work so agents execute safely while humans stay accountableTechnologies you will work with include:AI-assisted development with Cursor and agentic coding workflowsCloud & Infra: Google Cloud Platform, GKE (Kubernetes), Cloud Run, Terraform/IaC, VercelMessaging & IoT: Eclipse Hono, MQTT, MenderData & BI: PostgreSQL, BigQuery, SQLMesh, LookerObservability: Datadog, OpenTelemetryLanguages: TypeScript (Nest.js), Java, Go, Flutter, Ruby on RailsDevOps: CI/CD pipelines (GitHub Actions)Linear, Notion, Figma, MiroYour profileExtensive hands-on experience in software development with multiple general-purpose programming languages for a minimum of 5 yearsA proven track record of architecting scalable and secure systems, demonstrating a strong commitment to qualityExtensive experience in designing and implementing APIs that enable seamless integration and system communicationAn agile and result-oriented mindset, with a strong emphasis on collaboration and teamworkExperience communicating with stakeholders in business terms and understanding the technical implications of their requirementsIndustry-leading experience driving cross-functional teams and enforcing engineering alignment in fast-paced environments, including making and following through on critical technical decisionsExperience designing systems and APIs for agent consumption, with structured errors and clear contracts that let agents self-correctCapability to guide an engineering team through the shift to agentic engineering, reshaping workflows so agents execute safely while humans stay accountable for every outcomeStrong verbal and written communication skills in English, with proficiency in German considered a plusBenefitsYou are part of an international, dynamic, and highly motivated team of people who have proven to make things happenWith your work, you accelerate the "energy transition" and hence have a direct impact on our climateWork with and learn from other super-smart colleaguesYou will enjoy direct contact with core decision-makersYou will enjoy the best chances of entering full-time in one of Europe’s most thriving scaleupsYou work remotely (Germany-wide), with offices in Hamburg, Berlin or MunichCreate a healthy balance alongside your work and enjoy all the benefits of the EGYM WellpassBenefits and discounts are yours with FuturebensWhether city bike or e-bike - be flexible with our job bike leasing and do something good for the environment at the same timeIndividualised opportunities for professional developmentReporting directly to the CTOAbout us"At 1KOMMA5, our vision is to accelerate CO2 neutral life for all! We created an easy one-stop-shop to buy and install solar, charging stations and heat pumps, with the purpose of liberating all European homes from the shackles of fossil fuels. With Heartbeat, we make clean energy smarter. Connecting our customers into one powerful clean energy operating system to enable flexible tariffs and to ultimately follow the rhythm of wind and sun!" - Philipp Schröder (CEO 1KOMMA5)