Castle raises their Series A round of $9.2 million Learn more
Flexible Pricing

Plans that scale with your user growth

Start protecting your users today with our 14 day trial, no credit card required.


Monitor user activity to understand whether to take further action.


500 Monthly Active Users
  • Track API
  • Analytics
  • Slack Email & Alerts
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Automate security by letting your users review and mitigate potential threats.

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All Standard Features
  • Authenticate API
  • Device Management API
  • Webhooks
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Personalized support, dedicated Slack channel and enterprise SLA.

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All Professional Features
  • SLA
  • Data Import/Export
  • Dedicated Slack channel
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Protecting accounts for leading companies and products

Developers First

Our public documentation and our developer friendly support make it a pleasure for every developer to work with Castle on any platform or any stack.

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Open-source Mindset

We provide libraries for most programming languages and mobile platforms on GitHub. We also believe in contributing to any communities we're part of.

Castle on GitHub

Frequently Asked Questions

What is a monthly active user?
A monthly active user is a unique user who has created a session with Castle since the beginning of the billing cycle. A session is created either when a page view or a REST API event is tracked for a logged in user. It doesn't matter how long they stay logged in, or how many events they track, they're only counted once per month.
How is pricing calculated when my monthly active users change?
Your price can increase or decrease based on the total number of tracked monthly active users increasing or decreasing.
Is there a free trial?
Yes, you are able to make full use of all Castle features for free up until 500 MAU.
What if I decide to cancel?
If you no longer wish to use Castle, you can cancel at any time. At that point, your subscription will last until the end of the current monthly billing cycle.