SENIOR FOUNDING ENGINEER

Overview

We now handle millions of calls per month and need an engineer who has worked at that scale before and knows how to build systems that don't break under it. This is an architecture-heavy, full-stack role, not just backend. You will own everything from database optimization to reducing dashboard load times from four seconds to sub-100 milliseconds.

We're looking for someone in their late 20s who has moved fast inside engineering teams that move fast, brings solid practices into a growing codebase, and is the kind of person who has put hundreds of hours into mastering something outside of work. If you've never taken a hobby to an extreme, this is not the role for you.

You will work on-site at the SF office (moving to a larger space in three months), directly with the founding team.

About the Company

The company is the world's first quality assurance agency for voice and text AI, building the simulation, evaluation, and observability layer for conversational AI agents. Founded by former AI engineers at Microsoft and AWS, the company makes sure AI agents perform as intended before they ever reach the real world.

Backed by Y Combinator, Floodgate, and PeakXV, the company grew to over $100K in ARR in under a month during YC and has been doubling growth every three months since inception. They have crossed the $1M revenue mark and are now handling millions of calls per month. Clients include Google, DoorDash, Sallie Mae, and 11X, with more Fortune 500 names being added every quarter.

Key Responsibilities

• Architect and develop systems that simulate, analyze, and evaluate conversational AI agents across voice and multimodal formats

• Design resilient, scalable infrastructure using AWS (Lambda, EC2, WebSockets, SIP) to handle millions of real-time conversations

• Reduce system bottlenecks across the stack, from database query optimization to frontend dashboard performance

• Develop algorithms and pipelines that surface insights, detect failure modes, and ensure agents are safe, reliable, and aligned with human intent

• Establish and enforce strong engineering practices across code review, architecture design, and system design

• Work on-site with customers to build, sell, and deploy the product in real environments

Requirements — Must Have

• 6+ years of full-stack engineering experience with demonstrated depth across frontend and backend

• Deep proficiency in TypeScript, Python, SQL, and AWS (non-negotiable)

• Strong systems and architecture thinking — can design at scale and articulate why

• Experience building and optimizing production systems at a significant scale (millions of requests, large data volumes)

• Low ego, high communication ability; if you're hard to talk to, it's not a fit

• Has taken something outside of work to an extreme (competitive gaming rank, sub-12-second Rubik's Cube solve, athletic record, anything that required hundreds of hours of deliberate practice to achieve)

• US citizenship or permanent residency strongly preferred

• H-1B transfer considered

Tech Stack

• Frontend: React, Tailwind, TypeScript, NextJS

• Backend: Python, FastAPI, Supabase, Redis, AWS (Lambda, EC2, WebSockets, SIP)

• Voice AI: LiveKit, Deepgram, Cartesia, ElevenLabs, Gemini

• Other: WebSockets, CI/CD

Requirements — Nice to Have

• Prior experience as a founding engineer at a YC company (6+ months)

• Background in voice AI or conversational AI systems

• Has built polished, high-quality frontend web products

• Technical ex-founder with VC-backed startup experience

• Background at high-bar AI companies

Compensation

• Base Salary: $200,000 - $250,000

Benefits & Perks

• Health insurance

• Gym membership comped if you go 5+ times per month

• $500 desk and workspace setup stipend

Interview Process

1. Intro call with Founder

2. Take-home assignment

3. Technical interview

4. On-site work trial

5. Offer Extended