> ## Documentation Index
> Fetch the complete documentation index at: https://docs.authsignal.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Welcome to Authsignal Docs

> All the guides and resources you need to get started with Authsignal.

## Authsignal fundamentals

### What you can build

Authsignal enables you to implement various authentication patterns like passwordless login, MFA, adaptive MFA, and step-up authentication that integrate seamlessly with your existing identity stack.

<CardGroup cols={2}>
  <Card title="MFA" icon="shield-halved" iconType="solid" href="/actions-rules/actions/implementing-mfa">
    Add strong security with multiple authentication factors for your users.
  </Card>

  <Card title="Adaptive MFA" icon="shield-check" iconType="solid" href="/actions-rules/rules/adaptive-mfa">
    Apply MFA intelligently based on user behavior and risk signals.
  </Card>

  <Card title="Passwordless login" icon="fingerprint" iconType="solid" href="/actions-rules/actions/passwordless-login">
    Eliminate passwords while enhancing security and user experience.
  </Card>

  <Card title="Step-up auth" icon="lock" iconType="solid" href="/actions-rules/actions/getting-started">
    Require additional verification for sensitive operations.
  </Card>
</CardGroup>

### How it works

Authsignal uses two core concepts to control authentication flows:

<CardGroup cols={2}>
  <Card title="Actions" icon="bolt" iconType="solid" href="/actions-rules/actions/getting-started">
    Security events in your application (like login, payment, or data access) that may require
    additional verification.
  </Card>

  <Card title="Rules" icon="list-check" iconType="solid" href="/actions-rules/rules/getting-started">
    Conditions and logic that determine when and how users should be challenged based on risk
    factors, user behavior, or business requirements.
  </Card>
</CardGroup>

### Implementation approaches

Choose the approach that best fits your application:

<CardGroup cols={2}>
  <Card title="Pre-built UI" icon="window-maximize" iconType="regular" href="/implementation-options/prebuilt-ui/overview">
    Hosted components with fast setup and customizable styling to match your brand.
  </Card>

  <Card title="Custom UI" icon="laptop-code" iconType="solid" href="/implementation-options/web-sdk">
    Complete control over design using our client SDKs for web and mobile platforms.
  </Card>
</CardGroup>

## Popular integrations

Works seamlessly with leading identity providers, allowing you to enhance your existing auth infra:

<CardGroup cols={2}>
  <Card title="AWS Cognito" icon="aws" iconType="regular" href="/integrations/aws-cognito">
    Extend Cognito with passkeys and advanced authentication options.
  </Card>

  <Card title="Microsoft Azure AD B2C" icon="microsoft" iconType="solid" href="/integrations/azure-ad-b2c">
    Integrate with Azure B2C using Technical Profiles and OpenID Connect.
  </Card>

  <Card title="Duende IdentityServer" icon="server" iconType="solid" href="/integrations/identityserver/getting-started">
    Add Authsignal to IdentityServer for custom authentication workflows.
  </Card>

  <Card
    title="Auth0"
    icon={
  <svg
    xmlns="http://www.w3.org/2000/svg"
    className="icon icon-tabler icon-tabler-brand-auth0"
    width="28"
    height="28"
    viewBox="0 0 24 24"
    strokeWidth="2"
    stroke="#8b7bff"
    fill="none"
    strokeLinecap="round"
    strokeLinejoin="round"
  >
    <path stroke="none" d="M0 0h24v24H0z" fill="none"></path>
    <path d="M12 14.5l-5.5 3.5l2 -6l-4.5 -4h6l2 -5l2 5h6l-4.5 4l2 6z"></path>
    <path d="M20.507 8.872l-2.01 -5.872h-12.994l-2.009 5.872c-1.242 3.593 -.135 7.094 3.249 9.407l5.257 3.721l5.257 -3.721c3.385 -2.313 4.49 -5.814 3.25 -9.407z"></path>
  </svg>
}
    href="/integrations/auth0"
  >
    Learn how to use our Auth0 integration to implement MFA with just a few lines of code.
  </Card>
</CardGroup>

## Explore authentication methods

Choose from various authentication factors to secure your applications:

<CardGroup cols={2}>
  <Card title="Passkeys" icon="key" iconType="solid" href="/authentication-methods/passkey/prebuilt-ui">
    FIDO2 passkeys for phishing-resistant, passwordless authentication.
  </Card>

  <Card title="Push notifications" icon="mobile" iconType="solid" href="/authentication-methods/push-notification">
    Secure authentication via push notifications to mobile devices.
  </Card>

  <Card title="Authenticator apps" icon="mobile-screen" iconType="solid" href="/authentication-methods/totp">
    Time-based one-time passwords (TOTP) using authenticator apps.
  </Card>

  <Card title="QR code" icon="qrcode" iconType="solid" href="/authentication-methods/qr-code">
    Device authentication by scanning QR codes for cross-device flows.
  </Card>
</CardGroup>