Founding Engineer

Summary

Cardinal is an AI platform focused on precision outbound sales. They are seeking a Founding Engineer to architect and build core AI agents and infrastructure, directly impacting revenue for numerous startups.

Responsibilities

• Architect and build the core AI agents and infrastructure that power precision outbound at scale
• Make them accessible through beautiful, intuitive interfaces
• Work directly with customers
• Shape product direction
• Own critical systems that drive revenue for 40+ YC companies and growing
• Build AI agents that discover hyper-targeted leads by understanding ideal customer profiles, conference attendees, hiring signals, and more
• Create real-time content monitoring systems that track what prospects are posting, sharing, and engaging with across social platforms
• Manage multi-channel sequence orchestration across email and LinkedIn, managing dozens of email domains and sender accounts
• Develop enrichment pipelines that validate emails, find phone numbers, and pull company data at scale
• Build polished user interfaces that turn complex outbound workflows into experiences sales teams can set up in minutes

Skills

• 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
• 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

Qualifications

Must Haves

• 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

Nice to Haves

• 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

Benefits

• US visa sponsorship: Yes
• Significant equity in a fast-growing company backed by Y Combinator.
• Full benefits — health, dental, vision, unlimited PTO.