As a Founding Engineer at this YC S25 startup, you will build the critical identity and communication layer for the agentic era. You will design high-throughput backend systems and APIs that serve as the inbox for AI agents, enabling them to communicate and authenticate as independent digital citizens in a rapidly expanding market.
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Learn about Jack
Founding Engineer at Generalcatalyst
Join a YC S25 startup backed by General Catalyst and Paul Graham as a Founding Engineer building the identity and communication layer for AI agents. If you're a high-bar systems engineer who wants to own core infrastructure processing 100M+ emails for a user base that doubles every two weeks, this is your chance to shape a new category of the internet.
About this role
Role overview
About the company
Finance
General Catalyst is a global venture capital and investment firm partnering with entrepreneurs from seed stage to growth, specializing in transformational investments across sectors including technology, healthcare, fintech, and applied artificial intelligence. Founded in 2000, the firm manages $40+ billion assets under management as of June 2025 and has a portfolio of over 800 companies such as Airbnb, Stripe, HubSpot, and Snap. With offices in San Francisco, New York City, Boston, Berlin, Bangalore, and London, General Catalyst collaborates with founders to drive innovation, global resilience, and technology transformation.
What you'll do
What you will do
- Design and implement intuitive APIs and abstractions that allow AI agents to operate as first-class citizens of the internet.
- Build and scale distributed systems and core infrastructure capable of processing over 100 million emails per day with low latency.
- Own projects end-to-end, from initial system design to production rollout, while collaborating directly with the founding team and customers.
Who you are
Who this is a fit for
- Strong backend and systems engineering background with experience shipping production-grade software at a high-growth tech company or startup.
- Deep understanding of distributed systems, cloud infrastructure, or developer tools, with a preference for messaging and protocol-heavy experience.
- High-velocity builder who thrives in ambiguity and obsesses over quality, detail, and solving complex problems from 0 to 1.
Why this role
Why this role is remarkable
- Work at the frontier of AI infrastructure with $6M in funding from General Catalyst, Paul Graham, and the CTO of HubSpot.
- Join a high-performance team of 8 hailing from NVIDIA, Amazon, and Optiver, currently doubling their user count every two weeks.
- True founding impact with significant equity and the opportunity to define a new category of the internet where agents outnumber humans.
Jack & Jill
How Jack & Jill work together
I get to know what you’re great at, then find roles you’d never find yourself.Ok, I'll go first. I'm Jack, an AI that gets to know you on a quick call, learning what you're great at and what you want from your career. Then I help you land your dream job by finding unmissable opportunities as they come up, supporting you with applications, interview prep, and moral support.
I recruit from Jack’s network and make the intro when I spot a great match.And I'm Jill, an AI Recruiter who talks to companies to understand who they're looking to hire. Then I recruit from Jack's network, making an introduction when I spot an excellent candidate.
Meet Jack
Jack gets to know what you're great at and what you want next, then searches 15 million jobs daily and helps you discover roles at companies like this.
How does this work?
Jack’s an AI agent for job searching and career coaching. He works for you.
Jill is the AI recruiter working for the company. She recruits from Jack’s network.
If it’s a match and the company wants to meet you, they’ll make the intro. In the meantime, if you’d like, Jack will send you excellent alternatives.