Founding Engineer

Cardinal – Founding Engineer

Full-time

• San Francisco, CA (In office)
• Engineering, Full Stack
• Any experience (new grads ok)
  
  

Salary: $160,000 – $235,000 USD

Equity: 0.50% – 1.50%

US visa sponsorship: Yes

Skills: Next.js, React, TypeScript, Python, FastAPI

As a Founding Engineer, you'll architect and build the core AI agents and infrastructure that power precision outbound at scale — then make them accessible through beautiful, intuitive interfaces. You'll work directly with customers, shape product direction, and own critical systems that drive revenue for 40+ YC companies and growing.

What You'll Build

AI agents that discover hyper-targeted leads by understanding ideal customer profiles, conference attendees, hiring signals, and more. Real-time content monitoring systems that track what prospects are posting, sharing, and engaging with across social platforms. Multi-channel sequence orchestration across email and LinkedIn, managing dozens of email domains and sender accounts. Enrichment pipelines that validate emails, find phone numbers, and pull company data at scale. Polished user interfaces that turn complex outbound workflows into experiences sales teams can set up in minutes.

WE'RE LOOKING FOR

2–6 years of experience building production systems and user-facing features. Full-stack expertise — strong with TypeScript, React, Next.js, and Python. Systems thinking — you understand distributed systems, concurrency, and performance optimization. Product mindset — you talk to customers, understand their pain, and ship solutions that solve real problems. High agency — you identify problems and fix them without being asked.

BONUS POINTS

Experience with AI/ML, particularly LLMs, prompt engineering, or building AI agents. Background in sales tech, CRM systems, or growth engineering. Experience with OpenSearch/Elasticsearch, Supabase/PostgreSQL, or Redis. Previous startup experience or experience building successful B2B SaaS products. Design sense — you can build UIs that don't just work, but feel great to use.

What We Offer

Significant equity in a fast-growing company backed by Y Combinator. Direct customer impact — your code powers outbound for dozens of high-growth startups. Work closely with 2x YC founders (Harvard/MIT CS) who've built and sold before. Competitive compensation — $160K–$235K base salary plus equity. Full benefits — health, dental, vision, unlimited PTO. San Francisco office — collaborate in-person with the team.

About Cardinal

Cardinal is the AI platform for precision outbound. "Spray and pray" outbound is dead — the best sales teams operate with extreme precision, but doing this well means stringing together 10+ tools and hiring a GTM engineer. Cardinal replaces all of that. Our AI agents find hyper-targeted leads, continuously monitor what prospects are posting on social media, generate personalized snippets based on shared context, and orchestrate end-to-end outbound workflows across email and LinkedIn. We also capture inbound from website visitors, product signups, and ad impressions — qualifying and routing them into sequences automatically. We run outbound for 40+ YC companies including Mintlify, Greptile, and Luminai, and we're growing fast.

Co-founders Devi and Jianna are 2x YC founders (S23, W26) and Harvard/MIT CS alums. Their last company, Leafpress, was an energy software company where they closed enterprise customers like Lindt and Honeywell from cold outbound. They know outbound because they've lived it.

INTERVIEW PROCESS

Intro call (30 min) — Meet a founder, learn about Cardinal, tell us about yourself

Technical screen (60 min) — Pair programming on a real problem similar to what you'd work on

Take-home project (3–4 hours) — Build a small feature end-to-end; we pay for your time

Onsite (3 hours) — Meet the team, system design discussion, culture fit

Offer — We move fast and aim to get you an offer within a week of your onsite

Time to hire: 14 days