[Remote] (Senior) Full-Stack Software Engineer - Financial Infrastructure & Payments (m/f/d)

Note: The job is a remote job and is open to candidates in USA. 1KOMMA5° is a CleanTech Unicorn on a mission to electrify everything and connect everyone to the future energy market through their AI-based software platform, Heartbeat AI. They are seeking a Senior Full-Stack Software Engineer to design and run billing, invoicing, and monetization systems that support the global energy transition, ensuring scalability, reliability, and performance while collaborating with various teams.ResponsibilitiesContribute as a Full-stack engineer within a team of self-driven software developersDesign, build, and maintain business-critical systems across the stack. From scalable backend services and APIs to performant, user-friendly frontends with reliable flows for invoices, payments, and subscriptions where they touch customers and financePartner with finance, operations, and product to translate complex, loosely defined billing requirements into clear, actionable technical solutions, including compliance-minded documents and audit-friendly reporting where neededOwn slices of the invoice lifecycle (generation, delivery, and archival), templating and localization, and reconciliation and reporting together with stakeholdersChampion clean architecture, component reusability, and maintainable UI patterns using modern frameworks (e.g. React, Next.js, or similar)Drive experiment-driven innovation and uphold strong engineering practices in testing, CI/CD, observability, and code qualityContinuously improve developer experience by reducing technical debt, automating workflows, and documenting key decisions and operational processesOperate effectively in an asynchronous, outcome-oriented environment, managing your work autonomously and maintaining clear communication through documentation and structured updatesContribute to lightweight project management by defining milestones, ensuring technical feasibility, and aligning engineering work with product goalsSkillsExperience writing maintainable, reusable, and testable code in TypeScript, with strong skills in both frontend frameworks and backend technologiesStrong understanding of API design, data modeling, and system integration (RESTful or GraphQL), including patterns for idempotent money movement and auditable billing events where relevantProven ability to own features end-to-end, from UX and architecture to deployment and monitoringA pragmatic, product-focused mindset that balances technical excellence with delivering customer value for regulated or finance-adjacent flowsCuriosity and initiative to explore new tools and methods that improve product quality and engineering efficiencyExcellent written and spoken English (German is a plus)Residency in GermanyBenefitsYou 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 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 timeCompany Overview1Komma5° is a home electrification and climatetech company that provides intelligent energy solutions and promotes a CO₂-neutral lifestyle. It was founded in 2021, and is headquartered in Hamburg, Hamburg, DEU, with a workforce of 1001-5000 employees. Its website is https://1komma5.com/.