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.
Enterprise-grade infrastructure that scales to hundreds of concurrent users — multi-tenant architecture with role-based access control, end-to-end encryption, SOC 2-ready audit logging, and rate limiting built in from day one.
Polished user interfaces that turn complex outbound workflows into experiences sales teams can set up in minutes.
We're Looking For
1–6 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.
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 — $200K–$250K 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.
Our Founding Team
Co-founders Devi and Jianna are 2x YC founders (S23, W26) and Harvard/MIT CS alums. Devi is Harvard CS dropout, and Prod alum. Jianna is an MIT CS alum, and Prod alum. Formerly software engineer at DoorDash, Nvidia, and Meta. Their last company, Leafpress sold to Johnson Controls (NYSE: JCI), an $80B enterprise. 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.
We've raised over $5M from top investors including Y Combinator, Audacious Ventures, and other world-class operators and technologists.
Time to hire: 14 days