Castle
Agent49Agent Readiness: 49/100. Top 25%. Measured by StartupHub.ai. Median 41.Trust87Data Trust: 87/100. Top 25%. Measured by StartupHub.ai. Median 61.Developer-grade infrastructure to stop bots, abuse, and fraud by transforming user behavior into real-time signals.
About
Castle provides developer-grade infrastructure designed to combat bots, abuse, and fraud. By analyzing user behavior to generate real-time signals, it enhances security for companies like Canva, Rockstar Games, and Atlassian. Their mission is to establish the internet's missing trust layer, scaling through...
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Key facts
- Website
- castle.io
- Headquarters
- San Francisco, United States
- Founded
- 2015
- Employees
- 52
- Total funding
- $9M (Series A)
- Business model
- B2B
Castle pricing
| Plan | Price |
|---|---|
| Free$5 included API usage (1,000 Risk and Filter requests or 5,000 IP lookups), 3 days data retention, 3 seats, 1 environment | $0 / month |
| Pro$200 included API usage (40,000 Risk and Filter requests or 200,000 IP lookups), 7 days data retention, 5 seats, 2 environments | $200 / month |
| EnterpriseCustom MTU or volume pricing, Up to 18 months data retention, Unlimited seats and environments | $4,000 / month |
Risk and Filter requests billed at $0.005 each and IP Intelligence requests at $0.001 per valid IP entity, both drawing from shared monthly API budget. Pro overages billed pay as you go at same rates.
Plans as published by Castle, checked September 2026. Current prices on castle.io
Funding rounds
| Date | Round | Amount | Lead investors |
|---|---|---|---|
| 12 Feb 2019 | Series A | $9M | Index Ventures |
Tech stack
Detected on castle.io, last scanned 6 Nov 2026. Run your own scan
- Frontend
- Astro, Tailwind CSS
- Analytics
- PostHog
- CMS / Builders
- Lovable, ReadMe, Ghost
- CDN
- Netlify
- Email provider
- Google Workspace, SendGrid
- Status page
- Statuspage
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Frequently asked
Is Castle trustworthy and reputable?
StartupHub's Data Trust & Reputation score for Castle is 87 out of 100, a trusted rating, based on site security posture, privacy practices, malware and phishing checks, and public reputation signals.
How much funding has Castle raised?
Castle has raised a total of $9M in funding. The most recent round on record is Series A.
How many employees does Castle have?
Castle has approximately 52 people on record.
SEC filings, insider activity, nonprofit links and pay benchmarks for Castle:
Company details: from public sources. Funding: no announced round on file. Ownership: not yet claimed by the company. Scores: measured by named tools; each links to its method. Our rules
