Software Engineer (Voice AI / Backend)

About the Role Join a small, high-velocity team at a seed-stage AI voice platform building the next generation of voice AI agents for B2C businesses. You'll own projects end-to-end, from core product decisions to technical architecture and production code, pushing frontier models to their limits to solve real customer problems across realtime audio, distributed systems, and applied AI. What You'll Do Build fast, reliable voice AI systems including no-infra RAG, dynamic LLM routing, and shadow-testing new transcribers before production rollout. Design and operate a distributed call scheduler that handles load, race conditions, time zones, retries, and provider limits across many concurrent calls. Extend agents beyond voice to multi-channel interactions (calls, WhatsApp, email) with shared memory and state across async and realtime conversations. Build memory and reasoning systems so agents maintain context throughout entire customer flows. Develop an AI coworker that configures agents, debugs issues, and integrates with CRMs, calendars, and email. Make every bad call easy to trace to root cause, and keep the system resilient when calls, workers, or providers fail. What We're Looking For Production experience building and owning distributed systems at scale, including handling race conditions, load balancing, and fault tolerance. Strong proficiency in Python (FastAPI) and/or TypeScript (Node.js, Bun, Fastify), with a track record of shipping code end-to-end. Experience with real-time systems, audio processing, or voice infrastructure is a strong plus. Hands-on experience with LLMs, AI models, or agentic systems in production. Familiarity with PostgreSQL, Redis, or similar data stores in production environments. Experience with AWS, GCP, or Azure infrastructure. Familiarity with workflow orchestration tools such as Temporal, message queues, or similar. Experience with observability tooling such as OpenTelemetry, Honeycomb, or equivalent. React or full-stack experience is a welcome addition. Bias toward action: comfortable working independently, challenging assumptions, and driving outcomes. Team-first mindset with genuine care for business impact, not just the technology. Compensation & Benefits Salary: €85,000 to €160,000 annually, depending on experience. Equity included. Visa sponsorship available. Relocation support available for candidates moving to Berlin. Location On-site in Berlin, Germany. This is a fully on-site role; remote work is not available. Relocation support is provided.