Start by choosing the right OpenID approach
The term “OpenID” can mean the older decentralized protocol, but most modern integrations use OpenID Connect (OIDC), which sits on top of OAuth 2.0 and supplies a standardized identity token (ID token). Before you begin, decide whether you need pure authentication (login) via OIDC or a more complex authorization scenario that also requires access tokens for APIs. Choosing OIDC is usually the correct path for web and mobile apps because it simplifies consistent token formats, discovery, and standard validation steps.
Prerequisites and preparation
Gather the basics before you touch code: an account with an OpenID provider (for example a hosted identity provider or your company’s identity server), a domain or localhost address for testing, and a development environment where you can store client credentials securely. Also decide the application type (single-page app, server-side web app, native mobile app, or machine-to-machine). That choice determines which OAuth/OIDC flow you’ll implement and whether you’ll use a client secret or PKCE (Proof Key for Code Exchange).
Step 1 , register your application with the provider
Most providers offer a developer console where you create a new client/application. During registration you will provide a name, a description, and one or more redirect URIs (sometimes called callback urls). The provider will return a client identifier (client_id) and, in many cases, a client secret (client_secret) for confidential clients. Keep these credentials private; never embed secrets in public client code such as single-page apps or shipped mobile binaries.
Key values to note after registration
- client_id , public identifier for your app.
- client_secret , required for confidential server-based apps; store securely.
- redirect_uris , exact URLs the provider can redirect to after authentication.
- issuer or discovery url , the provider’s base URL used for discovery.
Step 2 , Configure redirect URIs, scopes, and grant types
Redirect URIs must match exactly the values registered with the provider. Choose scopes based on the data you need: openid is required for OIDC and typically you add profile and email to receive basic user attributes. For server-side authorization code flow, enable the authorization_code grant. For public clients (single-page apps or native), prefer authorization code with PKCE to avoid exposing tokens directly in the browser or app.
Step 3 , Implement the authorization code flow (typical web app)
The authorization code flow splits authentication into two steps: obtaining an authorization code from the provider via the user’s browser, then exchanging that code on the server for tokens. Begin by redirecting the user to the provider’s authorization endpoint with parameters: response_type=code, client_id, redirect_uri, scope (including openid), and a random state value to prevent CSRF. If you support PKCE, include code_challenge and code_challenge_method in the initial request and retain the generated code_verifier on the server for the next step.
Example authorization request (outline)
GET /authorize?
response_type=code&
client_id=YOUR_CLIENT_ID&
redirect_uri=
scope=openid%20profile%20email&
state=RANDOM_STATE
[&code_challenge=...&code_challenge_method=S256]
host: provider.example
Step 4 , Exchange the authorization code for tokens
After the provider redirects back to your redirect URI with code and state, validate that the state matches what you generated earlier. Then perform a server-to-server POST to the provider’s token endpoint. Include grant_type=authorization_code, the received code, redirect_uri, client_id, and client_secret for confidential clients; include the code_verifier if you used PKCE. The provider will return a json payload that typically includes id_token, access_token, token_type, and expires_in.
Example token exchange (curl)
POST /token
Content-Type: application/x-www-form-urlencoded
grant_type=authorization_code&
code=AUTH_CODE&
redirect_uri=
client_id=YOUR_CLIENT_ID&
client_secret=YOUR_CLIENT_SECRET
Step 5 , Validate the ID token
Always validate the ID token before trusting its claims. ID tokens are JWTs and must be validated in several ways: confirm the token signature using the provider’s public keys (available via a JWKS endpoint from the provider’s discovery document), check that the issuer (iss) matches the expected issuer URL, ensure the audience (aud) includes your client_id, verify the token hasn’t expired (exp), and validate the nonce if you used one to mitigate replay attacks. Libraries handle most of this work for you, but understanding the checks helps diagnose issues.
Validation checklist
- Signature verified using provider public keys (JWKS).
- iss equals expected issuer URI.
- aud contains your client_id.
- exp is in the future.
- nonce matches (if used).
Step 6 , Use and refresh tokens securely
Use the ID token to authenticate the user within your application and the access token to call protected APIs. For long sessions, use refresh tokens (if granted) to obtain new access tokens without user interaction. Store tokens on the server in encrypted storage or in secure browser cookies with HttpOnly and Secure flags for web sessions. Avoid storing tokens in localStorage in browsers because of XSS risks. For single-page apps, prefer short-lived access tokens and refresh via a secure backend or using refresh token rotation if supported by the provider.
Step 7 , Implement logout and session revocation
Provide a way for users to sign out of both your app and the identity provider. Many providers support a logout endpoint that you can redirect to, optionally supplying an id_token_hint and a post_logout_redirect_uri. When a user signs out, clear server-side sessions and remove any cookies or tokens. If the provider supports token revocation, call the revocation endpoint to invalidate refresh or access tokens so they cannot be used later.
Security considerations and best practices
Security matters at every step. Use https for all endpoints to avoid token interception. Prefer authorization code flow with PKCE for public clients to mitigate interception of the authorization code. Rotate client credentials if you suspect a leak and use short token lifetimes. Enable multi-factor authentication at the identity provider for sensitive accounts. When validating tokens, rely on the provider’s discovery document (/.well-known/openid-configuration) to fetch correct endpoints and the JWKS URI automatically instead of hard-coding values that could change.
Troubleshooting common issues
Many configuration problems stem from mismatched redirect URIs, incorrect client_id or client_secret, clock skew causing token validation failures, or missing scopes so the provider doesn’t include expected claims. When a token fails validation, inspect the raw token, verify the issuer and audience, and fetch the provider’s JWKS to confirm key IDs (kid) line up. Use provider logs or developer consoles that show failed requests and error codes; they often point straight to a bad redirect_uri, invalid grant, or insufficient scope.
Summary
Configuring OpenID Connect is a predictable sequence: register your application with the provider, set accurate redirect URIs and scopes, implement an appropriate OAuth/OIDC flow (authorization code with PKCE for most modern apps), exchange codes for tokens, validate ID tokens securely, and manage tokens and logout correctly. Use provider discovery and standard libraries to reduce risk and simplify implementation, and always follow security best practices around token storage and validation.
FAQs
Do I need a client secret for all apps?
No. Confidential server-side apps can safely use a client secret, but public clients like single-page or native mobile apps should not embed secrets. For public clients use PKCE to secure the authorization code flow without a secret.
What is the difference between OpenID and OpenID Connect?
OpenID Connect is the modern authentication layer built on OAuth 2.0 and provides standardized ID tokens and discovery endpoints. The older OpenID protocol is largely obsolete for new integrations; choose OpenID Connect for consistent support and tooling.
How do I validate an ID token?
Validate the JWT signature using the provider’s JWKS keys, verify iss and aud fields, check exp (and iat if needed), and confirm nonce if you used one. Many OIDC libraries perform these checks automatically.
Can I use OpenID Connect for API access?
Use the access token from an OIDC flow to call APIs. ID tokens are for authentication and identifying the user; access tokens are meant for authorization to resources. Ensure APIs validate access tokens properly (signature, issuer, audience, scopes).
Where can I find provider endpoints like token and JWKS?
Use the provider’s discovery document, typically at /.well-known/openid-configuration under the issuer base URL. It lists authorization and token endpoints, JWKS URI, supported scopes, and other configuration details useful for automated client setup.
