Castle

aid: castle
name: Castle
description: Castle is a fraud and account-abuse prevention platform that stops bots, credential stuffing, account takeover,
  and multi-accounting through behavioral analysis and device fingerprinting — without CAPTCHAs or puzzles for legitimate
  users. Developers integrate a client-side SDK (browser and mobile) that generates a short-lived request token, then call
  Castle's backend Risk API and Filter API to score authentication and transaction events in real time. Castle returns machine-learning
  risk scores and signals (bot, proxy/VPN, residential proxy, impossible travel, device reputation) that drive a policy rules
  engine, Lists, and webhooks. It serves security and trust-and-safety teams across gaming, fintech, marketplaces, and SaaS.
url: https://raw.githubusercontent.com/api-evangelist/castle/refs/heads/main/apis.yml
x-type: company
x-source: vc-portfolio
x-backed-by:
- index-ventures
x-tier: stub
x-tier-reason: portfolio-lead
accessModel:
  pricing: unknown
  onboarding: self-serve
  trial: false
  try_now: false
  public: false
  label: Self-serve signup
  confidence: medium
  source:
  - authentication
  generated: '2026-07-22'
  method: derived
specificationVersion: '0.20'
created: '2026-07-17'
modified: '2026-07-18'
image: https://castle.io/og.png
tags:
- Company
- Security
- Fraud Prevention
- Bot Detection
- Device Fingerprinting
- Account Takeover
- Risk Scoring
- Identity
maintainers:
- FN: Kin Lane
  email: kin@apievangelist.com
- FN: APIs.json
  email: info@apis.io
apis:
- aid: castle:castle-api
  name: Castle API
  description: Castle's REST API for real-time fraud and abuse detection. The Risk API scores authenticated user events (login,
    transaction, profile update), the Filter API scores anonymous/pre-authentication events (registration, password reset),
    the Log API records events without scoring, and the enterprise Events API queries and aggregates historical events. Device
    and Lists endpoints manage device reputation and allow/deny lists.
  humanURL: https://reference.castle.io
  baseURL: https://api.castle.io
  tags:
  - Fraud Prevention
  - Bot Detection
  - Risk Scoring
  properties:
  - type: Documentation
    url: https://docs.castle.io/
  - type: APIReference
    url: https://reference.castle.io
  - type: GettingStarted
    url: https://docs.castle.io/docs/integration-guide
  - type: Authentication
    url: authentication/castle-authentication.yml
  - type: Webhooks
    url: asyncapi/castle-webhooks.yml
common:
- type: TrustCenter
  url: security/castle-trust-center.yml
- type: DomainSecurity
  url: security/castle-domain-security.yml
- type: Website
  url: https://castle.io
- type: DeveloperPortal
  url: https://docs.castle.io/
- type: Documentation
  url: https://docs.castle.io/
- type: APIReference
  url: https://reference.castle.io
- type: GettingStarted
  url: https://docs.castle.io/docs/integration-guide
- type: Support
  url: https://castle.io/contact
- type: Blog
  url: https://blog.castle.io/
- type: GitHubOrganization
  url: https://github.com/castle
- type: Pricing
  url: https://castle.io/pricing
- type: SignUp
  url: https://dashboard.castle.io/signup/new
- type: Login
  url: https://dashboard.castle.io/login
- type: TermsOfService
  url: https://blog.castle.io/terms
- type: PrivacyPolicy
  url: https://blog.castle.io/privacy
- type: StatusPage
  url: https://status.castle.io
- type: Compliance
  url: security/castle-trust-center.yml
- type: Packages
  url: packages/castle-packages.yml
- type: SDKs
  url: packages/castle-packages.yml
- type: LLMsTxt
  url: llms/castle-llms.txt
- type: Authentication
  url: authentication/castle-authentication.yml
- type: Conventions
  url: conventions/castle-conventions.yml
- type: Sandbox
  url: sandbox/castle-sandbox.yml
- type: Lifecycle
  url: lifecycle/castle-lifecycle.yml
- type: ChangeLog
  url: changelog/castle-changelog.yml
- type: Conformance
  url: conformance/castle-conformance.yml
- type: ErrorCatalog
  url: errors/castle-problem-types.yml
- type: DataModel
  url: data-model/castle-data-model.yml
- type: Components
  url: components/castle-components.yml
- type: MCPServer
  url: mcp/castle-mcp.yml
- type: Webhooks
  url: asyncapi/castle-webhooks.yml
- type: AgentSkill
  url: skills/_index.yml
x-enrichment:
  date: '2026-07-19'
  status: backfilled
  pass: local-v1
  note: backfilled from .gitignore signal + verified work evidence