Software Engineer - Founding Team (Ex-Founder/CTO) gesucht in Berlin

We are looking for a product-minded early engineer who can own projects end-to-end across the full stack. You will work directly with the founder, talk to clients, and build the product hundreds of clients use every day. This is not a ticket-following role. You will be expected to spot problems, suggest solutions, and move fast.

What you will work on

• Build core product features end-to-end, from idea to production - frontend, backend, and everything in between.
• Take full ownership of projects: scope, architecture, implementation, and rollout.
• Build and improve backend services, data pipelines, and integrations with ERPs, payment platforms, and external APIs.
• Build and refine the interfaces clients interact with daily.
• Jump onto critical initiatives and unblock them fast.
• Work closely with the founder to shape what we build next.
• Talk to clients. You will understand why you are building something before you build it.

What we are looking for

• Product instinct: you think about the user before you think about the implementation.
• Senior/Staff level experience in early-stage startup engineering teams, or ex-founder/CTO.
• Strong across the full stack: TypeScript, React, Next.js on the frontend; Python and FastAPI on the backend.
• Experience with Supabase or similar Postgres-backed infrastructure - you can design schemas, write migrations, and debug queries.
• Familiarity with LLM APIs, prompt engineering, or AI agent frameworks.
• You have shipped and operated production systems, not just built them.