How do I set up an identity provider for passwordless auth and social login in our product?

To set up an identity provider (IdP) for passwordless authentication and social login, you typically use a hosted auth platform or a standard protocol like OAuth 2.0 / OpenID Connect (OIDC).

Here’s a practical way to think about it:

1) Pick an identity provider

Choose an IdP that supports:

• Passwordless login: magic links, email OTP, SMS OTP, passkeys/WebAuthn
• Social login: Google, Apple, Microsoft, GitHub, etc.
• OIDC/OAuth2 support
• User management and token issuance

Common options:

• Auth0
• Okta
• AWS Cognito
• Firebase Auth
• Azure AD B2C
• Clerk
• Supabase Auth
• Keycloak (self-hosted)

If you want flexibility and enterprise features, Auth0/Okta are common. If you want self-hosted control, Keycloak is a strong option.

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2) Decide your auth flows

For modern apps, the usual pattern is:

Social login

Use OAuth 2.0 / OIDC Authorization Code Flow with PKCE

• User clicks “Continue with Google”
• Redirect to IdP
• User authenticates at Google
• IdP returns an authorization code
• Your app exchanges it for tokens

Passwordless

Common approaches:

• Magic link: user enters email, receives link, clicks to log in
• Email OTP: user enters one-time code from email
• Passkeys/WebAuthn: user uses device biometrics or security key

Passkeys are the strongest passwordless option today; magic link is easiest to adopt.

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3) Create and configure the application in the IdP

In the IdP console:

• Create a new application/client
• Set:
  • Redirect URIs: where users return after login
  • Logout URIs
  • Allowed origins / CORS
• Configure token settings:
  • ID token / access token audience
  • scopes like openid profile email
• Enable the login methods:
  • Social providers
  • Passwordless email/SMS/passkeys

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4) Configure social identity providers

For each provider:

• Create an app in the provider’s developer console:
  • Google Cloud Console
  • Apple Developer
  • Meta for Developers
  • Microsoft Entra
• Get:
  • Client ID
  • Client Secret
• Add those values to your IdP
• Set the provider’s redirect/callback URL to the IdP’s callback endpoint

Typical setup example:

• User logs in with Google
• Google redirects to your IdP
• IdP maps the user to a profile and issues OIDC tokens to your app

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5) Configure passwordless

If your IdP supports passwordless directly:

• Enable email magic link or email OTP
• Verify sender domain and email delivery provider
• Configure templates and link expiration
• Optional: add passkeys/WebAuthn

If you need to build this yourself:

• Generate a one-time login token
• Email the user a magic link with the token
• Validate token server-side
• Exchange it for your app session/JWT
• Make tokens short-lived and one-time-use

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6) Integrate with your app

Usually your frontend:

• Redirects users to the IdP login page or uses the IdP SDK
• Handles callback after login
• Stores session securely

Your backend should:

• Validate tokens using the IdP’s JWKS public keys
• Verify:
  • signature
  • issuer
  • audience
  • expiration
• Create your own app session if needed

Best practice:

• Use short-lived access tokens
• Use refresh tokens only if needed
• Prefer HttpOnly secure cookies for browser sessions

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7) Handle account linking

If a user signs up with:

• Google today
• Email magic link tomorrow

You should decide whether these are:

• Separate accounts, or
• Linked accounts for the same user

This is important to avoid duplicate user records.

Common linking rules:

• Match by verified email if safe
• Or require explicit linking in account settings
• Keep audit logs of linking events

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8) Add security and UX safeguards

Recommended:

• Enable MFA for sensitive users or admin roles
• Protect against account takeover:
  • rate limiting
  • token expiration
  • replay protection
• Verify email ownership before creating trusted accounts
• Use passkeys when possible
• Log auth events for auditing

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9) Test end-to-end

Test:

• New user signup with Google
• Existing user login with email magic link
• Token validation on backend
• Logout and session expiration
• Error paths: expired link, unverified email, revoked social consent

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10) Suggested implementation pattern

A common architecture:

• Frontend: OIDC login via hosted IdP or SDK
• Identity Provider: handles Google/Apple/email/passkey login
• Backend API: validates JWTs and authorizes requests
• Database: stores app-specific user profile and linked identities

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If you want a quick recommendation

For most products:

• Use Auth0 / Clerk / Supabase Auth / Cognito
• Enable:
  • Google + Apple login
  • Email magic link
  • Passkeys if available
• Use OIDC Authorization Code + PKCE
• Validate tokens in your backend
• Add account linking and audit logs

If you want, I can also give you:

1. a vendor comparison for Auth0 vs Cognito vs Clerk vs Keycloak, or
2. a step-by-step implementation for your exact stack (e.g. React + Node, Next.js, iOS/Android, etc.).