Sr Full Stack Engineer - Agentic AI (San Francisco)

Location: San Francisco, CA (hybrid) | Type: Full-Time

Underdog.io is a modern recruitment platform. One of our growing hiring partners is looking to hire a Sr Full Stack Engineer.

Build the Future of Work

A hyper-growth AI startup, backed by the premier investors behind OpenAI, Anthropic, and Notion. Our platform is pioneering the "agentic" shift in the workplace, deploying sophisticated AI employees to automate complex, repetitive workflows. The result? We free human teams to focus on higher-impact work, from accelerating innovation to improving patient outcomes.

Our traction speaks to the massive demand: we've scaled from $0 to multi-million ARR in just three months. Now, we're building the team to define the playbook for the next generation of work. This isn't just a job; it's a chance to architect the inevitable at the absolute frontier of AI.

Your Mission

As a Sr Engineer, you will be instrumental in building the core experience that allows users to create, manage, and collaborate with AI agents. You won't just write code; you'll shape our product, culture, and the very future of how work gets done.

In this role, you will:

1. Architect and evolve our visual automation builder, enabling users to construct sophisticated multi-agent workflows with intuitive, no-code ease.
2. Leverage AI to power smart, in-product features like prompt optimization suggestions and automated agent performance testing.
3. Develop groundbreaking UX for human-in-the-loop collaboration, allowing users to supervise automations, provide real-time assistance, and teach agents through feedback.
4. Partner directly with product and design to pioneer bold, innovative features on the frontier of agentic AI, turning visionary concepts into shipped reality.

Who We're Looking For

We need a builder who thrives on immense ownership and has the technical chops to execute with speed and quality.

Must-Haves:

1. 2+ years of professional software engineering experience, with deep proficiency in TypeScript and React.
2. A relentless bias for action. You embody show > tell and are willing to do whatever it takes to solve a problem.
3. Extreme agency and self-direction. You effectively prioritize, make decisions, and unblock yourself with minimal oversight.
4. A foundational sense of ownership; you take full responsibility for your projects and the health of your systems.
5. A background in Computer Science (or related field) OR a proven history of dropping out to build incredible things.
6. Located in or willing to relocate to San Francisco.

Our Tech Stack

1. Language: TypeScript
2. Frontend: Next.js, Shadcn, Tanstack, Tailwind, Zustand, Vite
3. Backend: Node, AI SDK, Hono, Drizzle, Postgres (Neon), Railway

What We Offer

1. Foundational Role: Be a key early team member at a fast-growing, ambitious company defining a new category.
2. Unparalleled Impact: Directly push the boundaries of what's possible with AI and shape our product and technical roadmap.
3. Top-Tier Resources: A modern, powerful stack and the latest tools to empower your best work.
4. Competitive Compensation: A strong salary and meaningful, early-stage equity.
5. Life/Work Balance: Unlimited PTO and incredible team offsites (past trips: Iceland, Lisbon, Cancun, Costa Rica).

For the Builders and the Relentless

If you're ready to move beyond theory and build the future of work alongside a small, focused team, we need to talk. Your code will not just be a feature; it will be a fundamental building block for the AI-native organization.

Apply now and include a link to something you've built.