Senior Software Engineer

1KOMMA5°At 1KOMMA5°, we are building Europe’s leading clean energy operating system — connecting solar, heat pumps, energy storage, and charging into one unified platform.As Senior Software Engineer for Contract Lifecycle Platform, you will own the technical architecture behind how we manage, automate, and connect contracts and energy partner integrations across the Heartbeat AI platform.Your focus will be on backend systems, ensuring that customer and energy contracts are reliably integrated with our payment and CRM systems to support scalable post-booking, activation, and billing workflows.You will work with a cross-functional team of 10 (Product Manager, Designer, Backend Engineers, Frontend, Mobile) and work closely with other product and platform teams to evolve our distributed architecture and integration landscape.Become a part of our mission and learn more about our Product & Tech teamYour missionLead Architecture: Design and evolve the contract lifecycle, covering creation, activation, provisioning, cancellation, and optimization flows.Drive Systems Integration: Own the technical strategy for connecting contract services with payment, CRM, and external energy partner APIs using asynchronous event-driven patterns (Pub/Sub, message queues, webhooks).Collaborate Across Domains: Work closely with Product, Design, and Platform teams to ensure contract and partner data flows are consistent and reliable across systems.Ensure Data Quality & Observability: Implement robust validation, monitoring, and tracing for integrations with external systems and internal services.Mentor and Guide Engineers: Coach team members in software design, integration best practices, and clean architecture principles.Contribute as SME: Act as Subject Matter Expert (SME) for the Contract Management domain: reviewing PRs, documenting core system behavior, and ensuring technical decisions align with the broader platform vision.Reliability:  Balance architectural vision with hands-on implementation, ensuring scalable, maintainable, and production-ready solutions.Technologies you will work with:Backend: NestJS (TypeScript), Node.js, Prisma, PostgreSQLArchitecture: Microservices, Event-driven design (Pub/Sub, queues), REST/GraphQL APIsIntegrations: CRM, Payment, Energy Partner APIsInfrastructure: Google Cloud Platform (Cloud Run, CloudSQL, BigQuery), TerraformDevOps & CI/CD: GitHub Actions, Datadog, Infrastructure as CodeFrontend (for integration context): React, Next.js, FlutterYour profile5+ years as a backend or fullstack engineer, with strong expertise in TypeScript/Node.js2+ years in a lead, staff, or senior engineer role, driving architectural initiativesStrong experience with system and data integration, especially CRM, payment systems, or subscription/billing platformsDeep understanding of contract-based workflows, state management, and event-driven systemsExperience with regulated industries (energy, fintech, healthcare, or similar) and understanding of compliance requirementsExperience designing and maintaining microservices at scale on cloud platforms (GCP preferred)Strong skills in API design, versioning, and data modelingUnderstanding of GDPR and data privacy regulationsExcellent communication and leadership skills — able to balance hands-on delivery with technical strategyFluent in English; German is a plusBonus points for:Experience in the energy, IoT, or utility sectorBackground with billing systems or contract automationFamiliarity with Domain-Driven Design (DDD) and clean architectureExposure to data quality management and compliance processesBenefitsYou are part of a dynamic team with people who prove every day that they can make things happen and move companies forward with great positive impactYou move in flat hierarchies and have short decision-making paths. You can learn a lot quickly and get involved at different levelsYou will be welcomed by a friendly and familiar teamYou are part of the energy transition and recognize in your daily work what purpose it servesYou can work in one of our offices in Hamburg, Berlin or MunichYou create 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 timeIf you read this to the end, include the word “rubberduck” in your application.About 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°)