Senior Back End (Node.js) Engineer (with AI Voice Agent experience)

We are looking for an experienced Node.js Engineer to build a critical business feature: a real-time AI Voice Agent capable of autonomous outbound calling. This is a technical product ownership role where you will architect the system from the ground up using Node.js.

You will be responsible for solving the "hard problems" of voice AI: latency optimization, handling user interruptions ("barge-in"), and noise cancellation. You will lead the implementation of our first non-English language (Dutch), working alongside native speakers for quality validation, and design the architecture to support future languages.

Main Responsibilities

• Voice Agent Development (Node.js): Build and maintain the core voice agent logic using Node.js, ensuring sub-second latency for a natural conversational feel.

• AI & Telephony Orchestration: Integrate Speech-to-Text (STT), LLMs, and Text-to-Speech (TTS) services (e.g., Deepgram, OpenAI, ElevenLabs) with telephony providers (e.g., Twilio, Vonage) into a seamless event-driven architecture.

• Latency & Interruption Handling: Implement sophisticated logic to handle "barge-ins" (when a user interrupts the bot) and silence detection, ensuring the bot stops speaking immediately and listens, just like a human would.

• Multi-Language Architecture: Design the codebase to support internationalization (i18n), starting with Dutch. Note: You do not need to speak Dutch; you will work with a Product Owner who handles linguistic testing.

• Infrastructure Selection: Evaluate and recommend telephony and Voice API providers if the current infrastructure is insufficient for production-grade AI voice calls.