Founding Software Engineer
About the Role
Join a Y Combinator-backed AI SaaS startup as their first engineering hire. The company is building an AI-powered motion design product that turns hours of animation work into minutes — already serving a rapidly growing user base. You'll work directly with the founders to shape the technical foundation, own end-to-end development, and help scale the product to millions of users.
What You'll Do
- Partner with founders to deliver user-centric product solutions from concept to production.
- Own end-to-end development of full-stack features with scalable architecture design.
- Build and optimize agentic LLM systems incorporating tool-calling, multi-step reasoning, and MCP protocols.
- Design comprehensive LLM evaluation frameworks with automated benchmarks, human-in-the-loop validation, and A/B testing.
- Optimize LLM inference performance, cost efficiency, and latency across multiple model architectures.
- Develop a high-performance motion graphics engine.
- Drive architectural decisions that support scalable growth to millions of users.
What We're Looking For
- 2+ years of software engineering experience with strong CS fundamentals.
- Proficiency in TypeScript (required) and ideally the broader stack: React.js, Next.js, PostgreSQL, GCP, AWS.
- Hands-on experience building or integrating LLMs, tool-calling, multi-step reasoning, and MCP protocols.
- Experience designing and implementing LLM evaluation frameworks — automated benchmarks, human-in-the-loop validation, and A/B testing.
- Proven ability to deliver end-to-end full-stack features with scalable architecture.
- Startup or early-stage company experience with a strong ownership mindset.
- Proficiency in optimizing LLM inference performance, cost efficiency, and latency across multiple model architectures.
Location
This role is fully on-site in Berlin, Germany. Visa sponsorship is not available.
Compensation
Salary range: €80,000 – €160,000 EUR annually, depending on experience. As an early founding engineer, you can expect meaningful equity alongside your base compensation.