About us

We're building trust infrastructure for the modern internet

Castle provides developer-grade infrastructure to stop bots, abuse, and fraud. We turn user behavior into real-time signals that power security for companies like Canva, Rockstar Games, and Atlassian. Our ambition is bigger than stopping abuse: we're building the trust layer the internet never got.

We scale through leverage, not headcount. Our credibility comes from the product itself, not a sales pitch. We build from first principles, trusting the intuition of a small, autonomous team to solve problems no playbook can address.

Castle is profitable, product-led, and growing fast. If you think in systems, move quickly, and default to ownership, you'll feel at home.

How we build

Principles that shape our product, our team, and our decisions.

Act like a founder

We believe the best work comes from people who act with the autonomy and responsibility of a founder. This means owning outcomes end-to-end, solving problems directly, and challenging ideas with intellectual honesty, regardless of title.

Intuition leads data

We trust human intuition as our most powerful, unmodelable signal. While data is critical, our best calls start with the gut feeling that something is misaligned. We listen to that signal above the noise because it's faster and more insightful than any dashboard.

AI is on the team

We treat AI as a core collaborator to accelerate our work and deepen our thinking. Its speed is a powerful tool, but it lacks human reasoning. We expect every team member to manage that partnership through prompting, refining, and debugging, while retaining full responsibility for the final judgment.

Build for leverage

We are committed to scaling through systems and automation. Our focus is on multiplying impact per person by building reusable workflows that compound over time. This allows a small, focused team to achieve an outsized impact.

Don't play by the book

We build from first principles. We believe the most innovative solutions come from breaking problems down to their root mechanics. Precedents are historical context that inform our thinking, but our creative process starts from a blank slate.

The product is the pitch

Our credibility is built on product capability. We demonstrate our value by sharing unique insights from our data and building a product so effective that it speaks for itself. We earn trust through transparent, technical content, and our team's role is to guide and amplify that truth.

Our backers