Senior Backend Engineer

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 Backend Engineer (Typescript) – Heartbeat AI (m/f/d), 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 about our Product & Tech team

• Lead 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), , Prisma, PostgreSQL
• Architecture: Microservices, Event-driven design (Pub/Sub, queues), REST/GraphQL APIs
• Integrations: CRM, Payment, Energy Partner APIs
• Infrastructure: Google Cloud Platform (Cloud Run, CloudSQL, BigQuery), Terraform
• DevOps & CI/CD: GitHub Actions, Datadog, Infrastructure as Code
• Frontend (for integration context): React, , Flutter

• 7+ years as a backend or fullstack engineer, with strong expertise in
• 2+ years in a lead, staff, or senior engineer role, driving architectural initiatives
• Strong experience with system and data integration, especially CRM, payment systems, or subscription/billing platforms
• Deep understanding of contract-based workflows, state management, and event-driven systems
• Experience with regulated industries (energy, fintech, healthcare, or similar) and understanding of compliance requirements
• Experience designing and maintaining microservices at scale on cloud platforms (GCP preferred)
• Strong skills in API design, versioning, and data modeling
• Understanding of GDPR and data privacy regulations
• Excellent communication and leadership skills — able to balance hands-on delivery with technical strategy
• Fluent in English; German is a plus

Bonus points for:

• Experience in the energy, IoT, or utility sector
• Background with billing systems or contract automation
• Familiarity with Domain-Driven Design (DDD) and clean architecture
• Exposure to data quality management and compliance processes

• You 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 impact
• You move in flat hierarchies and have short decision-making paths. You can learn a lot quickly and get involved at different levels
• You will be welcomed by a friendly and familiar team
• You are part of the energy transition and recognize in your daily work what purpose it serves
• You can work in one of our offices in Hamburg, Berlin or Munich
• You create a healthy balance alongside your work and enjoy all the benefits of the EGYM Wellpass
• Benefits and discounts are yours with Futurebens
• Whether city bike or e-bike - be flexible with our job bike leasing and do something good for the environment at the same time
  If you read this to the end, include the word "rubberduck" in your application.