Castle raises their Series A round of $9.2 million Learn more
About Us

Towards a passwordless future

The shift of responsibility to the customer must stop. It is about time that companies take the next step in securing their products, and we are here to help. Whether you're building a bitcoin service, e-commerce store, mobile app, or any other customer-facing application, Castle will have your users' accounts protected from fraud and hijacks within minutes. And the more we are, the better our algorithms will get at catching the bad guys. Maybe one day we won't even be needing those passwords anymore.


Castle was founded in Malmo, Sweden, by the two engineers Johan and Sebastian.

The Move


Johan and Sebastian moved to the Bay Area to participate in Y Combinator.

The Scale Up


Castle raises their Series A and is set to triple their team in the next 18 months.


We're on a mission to simplify account security

Take your work seriously. Not yourself

We spend a huge amount of our time at work. So the more that time doesn’t feel like “work,” the better. At the same time, we can be serious, without taking ourselves too seriously.

Trust and be trustworthy

Trust that everyone is here because they want to be. Trust each other to do what we say. Trust when we can’t we’ll let each other know. Trust that it’s ok to make mistakes.

Just build it

We believe the best way to learn if something will work is to just go do it. Our process is iterative, and we're constantly learning from the things we try. When in doubt, just build it.

San Francisco

The San Francisco office was founded in 2016

1663 Mission St #720, San Francisco


The Poland office was founded in 2017.

Podole 60, 30-394 Kraków, Poland


The Sweden office was founded in 2015.

Drottninggatan 38a, 211 45 Malmö, Sweden

Want to help us eliminate passwords?

We're a team of engineers, designers and security lovers. We'd love to have you onboard!
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