Founding AI Engineer (San Francisco)

Founding AI Engineer (YC-backed Voice + Text AI Startup)

Location : San Francisco, CA (in person)

Perks : Team housing available in San Francisco

The Company

Our client is a YC-backed seed-stage startup building the simulation, evaluation, and observability layer for voice and text AI agents . Their platform is already being used by enterprises and high-growth startups, including Fortune 500 companies, to ensure conversational AI agents perform safely, reliably, and at scale.

With $4M raised from leading investors (including Floodgate and PeakXV) and revenue doubling every quarter since launch, theyre now hiring a Founding AI Engineer to join their core team in San Francisco. This is a chance to work alongside the founders, directly influence the product roadmap, and help define the technical foundation of a rapidly growing AI company.

The Role

This is a full-stack role with a strong AI focus. The ideal candidate is hands-on, deeply technical, and comfortable building across the stack. Youll be designing systems that simulate, test, and measure AI agents in real time - powering the infrastructure that ensures AI products behave as intended.

Responsibilities

• Architect and develop systems that simulate, analyze, and evaluate conversational AI agents across voice and text.
• Design scalable, resilient infrastructure on AWS (Lambda, EC2, WebSockets, SIP) to handle thousands of simultaneous real-time interactions.
• Build and optimize pipelines that measure agent performance, detect failure modes, and enforce reliability and safety .
• Ship production-grade code across frontend and backend systems with full ownership from design to deployment.
• Collaborate directly with enterprise customers to build, test, and deploy solutions in real-world environments.

Tech Stack

Frontend : React, TypeScript, Next.js, Tailwind

Backend : Python, FastAPI, Redis, Supabase

Infrastructure : AWS (Lambda, EC2, WebSockets, CI / CD)

Voice AI : LiveKit, Deepgram, Cartesia, ElevenLabs

Text AI : Pydantic AI, OpenAI, agentic frameworks

Ideal Profile

Nice to Have

Logistics

Why Its Worth Your Time

This company is defining a new category for AI quality assurance - engineering trust into how AI agents are tested before deployment. Youll be working with high-profile customers, advanced AI systems, and founders who have already proven their ability to ship, sell, and scale.

If you want to build at the intersection of AI safety, infrastructure, and real-world impact , this is an opportunity to join a YC startup early, take real ownership, and grow with the company.

To express interest or learn more, reach out directly to Josh Kelly at HartleyCo , the retained search partner for this hire.