Founding Engineer - AI Agents (Voice + Infrastructure)

HartleyCo; San Francisco (CA); On-site; USD 120,000 - 180,000; Full time

Job summary

HartleyCo, a YC-backed startup in San Francisco, is building the testing and observability layer for AI agents. They’re tackling a core problem—how do you actually trust AI systems in production?

This is a founding engineer role in a small, high-caliber team with real traction and enterprise customers. You’ll own meaningful parts of the product from day one, ship quickly, and work across infrastructure and real-time systems.

Qualifications

• 1-3 years experience (flexible if you've built exceptional things).
• Strong engineering fundamentals (Python and/or React/TypeScript).
• Evidence of building and shipping real products.
• Comfortable moving fast without heavy structure.
• Interested in startups and high-ownership environments.
• Nice to have: Voice or real-time systems exposure.

Responsibilities

• Work across infrastructure: real-time systems, scaling thousands of interactions.
• Ship quickly, work directly with users, owning meaningful parts of the product from day one.

Skills

Python

React/TypeScript

Infrastructure design

Shipping real products

Job description

I'm working with a YC-backed startup building the testing and observability layer for AI agents.

They're tackling a problem most teams ignore until it breaks: how do you actually trust AI systems in production?

They've already:

• Raised ~$4M from top-tier investors
• Landed enterprise customers (including Fortune 500s)
• Reached meaningful ARR within weeks of launch
• Continued to scale rapidly since

This is not a \"build a wrapper\" role.

It's core infrastructure for a category that's about to explode.

The Role

This is a Founding Engineer position in a small, high-calibre team in San Francisco.

You'll work across:

• Infrastructure: real-time systems, scaling thousands of interactions

You'll be shipping quickly, working directly with users, and owning meaningful parts of the product from day one.

What They're Looking For

• 1-3 years experience (flexible if you've built exceptional things)
• Strong engineering fundamentals (Python and/or React/TypeScript)
• Evidence of building and shipping real products
• Comfortable moving fast without heavy structure
• Interested in startups and high-ownership environments

Nice to have:

• Voice or real-time systems exposure

Why This Is A Good Bet

• Real traction and real customers
• Technical founders (ex-AWS Bedrock / Microsoft Copilot)
• High ownership from day one
• Exposure across AI, infrastructure, and product
• The kind of environment where you compress years of learning into months

Details

• Small team, high bar, fast pace

If you're early in your career and want to work on hard problems, ship quickly, and accelerate your trajectory, this is worth a conversation.