Castle is building the Stripe of bot and fraud prevention.

A real-time engine that runs at the edge, protects apps in milliseconds, and replaces CAPTCHA-era friction with invisible defense. We’re a profitable, nimble team serving customers like Canva, Framer, and Atlassian. No salespeople, just a great product experience.

You’ll work directly with Johan (CEO + acting Head of Product) in a tight shaping loop. You won’t be handed roadmaps; you’ll co-design the product logic from first principles. Johan defines the strategic model; you define the system behavior that makes it real.

You’ll make final calls on user flow logic, system behavior, and product defaults, subject to alignment on philosophy and execution clarity.

Together with our Product Designer, Product Engineer, and Product Marketer, you’ll form the core product function. We don’t use PMs. We shape product directly.

Location

This is most likely an on-site Brooklyn role. You’ll be working closely with Johan on a day-to-day basis to define Castle’s behavior from the inside out.

For exceptional candidates, we’re open to remote if you can embed in NYC for 4–6 weeks during onboarding, and 1–2 weeks per quarter going forward.

What you'll do

• Define the logic behind key product concepts: what runs on the edge vs in-app, what APIs we expose, and how their behavior scales across tiers
• Decide what users see in free vs paid plans, what gets gated, and when we prompt them to upgrade
• Structure flows across endpoints, event tracking, policy creation, and blocking logic
• Define the default behaviors for blocked requests, scored requests, and anomalous patterns. When to alert, when to act
• Decide when to reveal vs hide complexity. Especially around detection, scoring, and policy behavior

What we’re looking for

• You’ve shaped real product systems—flows with complex logic, pricing gates, or state-based UX
• You think in behavior first, then interface
• You’d rather build the product with the founder than manage a roadmap at a big org
• Bonus points if you’ve worked in fraud, devtools, or infra. But clarity and taste matter more than domain.

How to apply

We don’t care about titles or degrees. We care if you can think clearly, move fast, and design products that make sense.

If this role sounds like it fits how your brain works, reach out directly to Johan on DM. Include links to anything that shows how you think; products, posts, mockups, memos, or just raw thoughts.