The top 3 examples of authentication methods for APIs (with real-world examples)

If you’re looking for practical examples of top 3 examples of authentication methods for APIs, you’re usually deciding between three families of approaches:

• API keys (simple shared secrets)
• OAuth 2.0 / OpenID Connect (OIDC) (delegated user and app access)
• Token-based auth, usually JWTs (signed, stateless tokens)

These aren’t abstract patterns. They show up in almost every major platform you use:

• Stripe, SendGrid, and Twilio lean heavily on API keys for server-to-server integrations.
• Google, Microsoft, and GitHub rely on OAuth 2.0 / OIDC for user login and third-party apps.
• Modern microservice platforms (Kubernetes-based backends, serverless APIs) increasingly pass JWTs between services.

The best examples of API security combine these methods: OAuth 2.0 to obtain a token, JWT as the token format, and an API gateway that also supports API keys for internal automation.

Example of API key authentication: simple, direct, and still everywhere

If you want a straightforward example of API authentication, API keys are where most teams start.

How API key authentication works in practice

An API key is just a long, random string that identifies a client. The server stores a hashed version of that key and checks it on every request. In code, it often looks like a header:

GET /v1/payments HTTP/1.1
Host: api.example.com
Authorization: Bearer sk_live_9a3f...  

or:

GET /v1/payments HTTP/1.1
Host: api.example.com
X-API-Key: 9a3f...  

These examples of API key usage are intentionally boring. That’s the appeal: they’re easy to generate, rotate, and document.

Real examples of API key usage

Some concrete, 2024–2025 examples include:

• Stripe: Uses secret API keys for server-side requests and restricted keys for limited scopes, with dashboard-based rotation.
• SendGrid: Issues API keys with fine-grained permissions (mail send, marketing, stats) so you can limit blast radius if a key leaks.
• Google Maps Platform: Uses API keys for many server-side map and geocoding calls, often combined with HTTP referrer or IP restrictions.
• Internal microservices: Many companies still use API keys between internal services behind a VPN or service mesh when OAuth feels like overkill.

These examples of top 3 examples of authentication methods for APIs show why API keys remain popular: low friction and good enough for many machine-to-machine use cases.

Strengths and limits of API keys

Strengths

• Easy for developers to understand and adopt.
• Simple to implement on both client and server.
• Work well for non-user, service-to-service calls.

Limits

• Keys are effectively passwords; if they leak, attackers get full access.
• No built-in concept of user identity, consent, or limited scopes.
• Harder to support fine-grained authorization unless you bolt on extra logic.

Security guidance from organizations like NIST (see NIST SP 800-204A) increasingly recommends more granular, token-based approaches for public-facing APIs. But API keys still have a place when combined with TLS, IP allowlists, rate limits, and strict rotation policies.

OAuth 2.0 and OpenID Connect: best examples for user-facing APIs

When people ask for examples of top 3 examples of authentication methods for APIs that support sign-in with Google, Microsoft, or GitHub, they’re really asking about OAuth 2.0 and OpenID Connect (OIDC).

How OAuth 2.0 shows up in real APIs

OAuth 2.0 is a framework for delegated authorization. A user grants an application limited access to their resources on another service, without sharing their password. In day-to-day API design, the best examples look like this:

• Your app redirects the user to Google or Microsoft.
• The user signs in and approves requested scopes (like email or calendar.read).
• Your app receives an authorization code, exchanges it for an access token, and then calls the API with that token.

A typical API call with OAuth 2.0 looks like:

GET /drive/v3/files HTTP/1.1
Host: www.googleapis.com
Authorization: Bearer ya29.a0AfH6SMB...

The server validates the access token and checks scopes to decide whether to allow the request.

Real examples of OAuth and OIDC

Here are some concrete examples of how this appears in 2024–2025:

• Google APIs: Use OAuth 2.0 and OIDC for everything from Google Drive to Gmail. Access tokens control API access; ID tokens (OIDC) carry user identity.
• Microsoft Graph: Uses OAuth 2.0 and OIDC for Microsoft 365 data. Apps request scopes like User.Read or Mail.Read and receive tokens from Azure AD.
• GitHub Apps: Use OAuth 2.0 to let third-party tools access repos and issues on behalf of a user or organization.
• Okta/Auth0/Identity providers: Issue OIDC ID tokens and OAuth access tokens for your own APIs, increasingly with passkeys or WebAuthn as the underlying sign-in method.

These are some of the best examples of how to secure APIs when you need user identity, consent, and granular scopes.

Why OAuth 2.0 / OIDC dominate modern API auth

Compared to simple API keys, OAuth and OIDC bring:

• User identity via ID tokens (subject, email, claims).
• Granular scopes that define what the token can do.
• Short-lived tokens with refresh tokens, reducing risk if a token is stolen.
• Standard flows for web, mobile, SPA, and machine-to-machine clients.

Organizations that care about compliance, especially in regulated sectors like healthcare and finance, tend to favor OAuth-based patterns. For example, US healthcare APIs influenced by the ONC’s interoperability rules often use OAuth 2.0 to let patients authorize apps to access their records.

Common pitfalls when using OAuth for APIs

Even the best examples of top 3 examples of authentication methods for APIs can go wrong in implementation. Frequent issues include:

• Treating access tokens as long-lived static secrets instead of short-lived credentials.
• Skipping TLS termination checks at the API gateway, exposing tokens in transit.
• Ignoring scope checks and treating any valid token as “full access.”
• Rolling custom OAuth servers instead of using tested libraries or identity providers.

The net result: OAuth gives you a powerful toolbox, but you still need disciplined API design and security reviews.

JWT and token-based auth: examples for microservices and stateless APIs

The third category in our examples of top 3 examples of authentication methods for APIs is token-based authentication, most often with JSON Web Tokens (JWTs).

How JWT authentication works

A JWT is a signed token, typically formatted as three Base64URL segments:

header.payload.signature

The header describes the algorithm, the payload contains claims (like sub, exp, aud, and roles), and the signature lets APIs verify that the token hasn’t been tampered with. A typical Authorization header looks like:

Authorization: Bearer eyJhbGciOiJSUzI1NiIsInR5cCI6IkpXVCJ9...

In many real-world examples, JWTs are issued by an OAuth 2.0 / OIDC provider and then consumed by your APIs and microservices.

Real examples of JWT use in APIs

Some concrete 2024–2025 examples include:

• Kubernetes + service meshes: Internal services authenticate requests using JWTs issued by an identity provider or service mesh control plane.
• Serverless APIs (AWS Lambda, Azure Functions, Google Cloud Functions): API Gateways validate JWTs before invoking functions, offloading auth from the function code.
• Single-page applications (SPAs): Frontends obtain JWT access tokens via OAuth/OIDC and attach them to API calls to a backend-for-frontend (BFF) or API gateway.
• B2B APIs: Many SaaS vendors issue JWTs to partner systems for short-lived, scoped access to sensitive operations.

These examples include some of the best examples of how to build stateless, horizontally scalable APIs: each service validates the JWT locally using a public key and doesn’t need to call back to a central session store.

Benefits and risks of JWT-based auth

Benefits

• Stateless verification: APIs can validate tokens locally.
• Rich claims support: embed roles, tenant IDs, and permissions.
• Interoperable: widely supported across languages and frameworks.

Risks

• Token bloat: Overloaded payloads increase header sizes and leak more data if tokens are logged.
• Revocation complexity: Harder to revoke tokens early without extra infrastructure (blacklists, short lifetimes, or introspection endpoints).
• Algorithm misuse: Misconfigurations (e.g., accepting none algorithm) have caused real security incidents.

Standards bodies and security researchers have written extensively about JWT best practices. While not API-specific, the security mindset echoed in resources like the NIST Cybersecurity Framework applies directly: minimize token lifetime, validate issuers and audiences, and log and monitor token usage.

Comparing the top 3 examples of authentication methods for APIs

When you put these examples of top 3 examples of authentication methods for APIs side by side, the tradeoffs become clearer.

When API keys make sense

Use API keys when:

• You’re exposing machine-to-machine APIs with no user context.
• You control both client and server and can store keys securely.
• You want a fast path to secure an internal or low-risk service.

Examples include:

• A CI/CD pipeline calling your deployment API with a rotated key.
• An internal reporting job querying analytics data overnight.

When OAuth 2.0 / OIDC is the right example of a solution

Use OAuth/OIDC when:

• You need user consent and clear scopes.
• You’re integrating with third-party identity providers (Google, Microsoft, Okta).
• You’re building a public API that third-party apps will call on behalf of users.

Examples include:

• A health app accessing patient data from a provider’s FHIR API with patient consent, aligned with US interoperability expectations.
• A SaaS tool syncing email and calendar data from Microsoft 365 using Microsoft Graph.

When JWT-based tokens shine

Use JWT-based token auth when:

• You’re running microservices that need to validate tokens independently.
• You want rich claims (tenant, roles, permissions) inside the token.
• You’re comfortable managing keys and token lifetimes.

Examples include:

• An internal platform where a gateway issues JWTs to downstream services.
• A multi-tenant SaaS backend that uses tenant IDs in JWT claims for authorization checks.

In practice, the best examples of top 3 examples of authentication methods for APIs don’t pick a single method forever. They combine them: API keys for internal automation, OAuth/OIDC for user-facing flows, and JWTs as the token format carried between services.

2024–2025 trends shaping API authentication examples

Several trends are reshaping how these top 3 methods are implemented:

Shorter token lifetimes and zero trust thinking

Organizations are pushing toward short-lived tokens and continuous verification. Instead of trusting a long-lived API key, they issue short-lived tokens via OAuth 2.0 or a central identity provider. This aligns with zero trust principles promoted by agencies like CISA, where every request is authenticated and authorized.

Passkeys and WebAuthn feeding into API auth

User authentication is shifting toward passkeys and WebAuthn, but the downstream effect hits APIs: identity providers still issue OAuth and OIDC tokens, but the backing credential is stronger than a password. The examples of top 3 examples of authentication methods for APIs don’t change in name, but the trust in the underlying user identity improves.

API gateways as the enforcement point

Modern gateways (Kong, Apigee, AWS API Gateway, Azure API Management) increasingly handle:

• API key validation and rate limiting.
• OAuth 2.0 token introspection and JWT verification.
• Centralized logging and anomaly detection.

This means your service code can focus on authorization logic (what the user or client is allowed to do) rather than re-implementing authentication.

Best practices when using these examples of authentication methods for APIs

Regardless of which method you choose, a few patterns show up in the best examples:

Always pair authentication with TLS

Whether you’re using API keys, OAuth tokens, or JWTs, transmit them only over HTTPS. Plain HTTP or misconfigured TLS invalidates all of your careful design.

Minimize scope and lifetime

• Give API keys the narrowest possible permissions.
• Use OAuth scopes aggressively to limit token power.
• Keep JWTs short-lived and refresh them via secure flows.

Rotate, monitor, and audit

• Rotate API keys regularly, and immediately after any suspected incident.
• Log token usage and analyze for anomalies (unusual IPs, geos, or volumes).
• Audit which services can issue or validate tokens, and who administers those systems.

Guidance from organizations like NIST and CISA repeatedly emphasize these patterns: identity is a moving target, and APIs must assume credentials can be stolen and misused.

FAQ: examples of API authentication questions teams actually ask

What are the best examples of authentication methods for APIs I should consider first?

For most teams, the starting point is:

• API keys for internal or low-risk service-to-service APIs.
• OAuth 2.0 / OIDC for user-facing and third-party-integrated APIs.
• JWT-based tokens for microservices that need stateless validation.

Those three give you a flexible toolkit that fits most real-world architectures.

Can you give an example of combining multiple authentication methods in one API?

Yes. A common pattern in 2025 looks like this:

• External clients authenticate users via OAuth 2.0 / OIDC with an identity provider.
• The identity provider issues JWT access tokens.
• An API gateway validates those JWTs and forwards requests to microservices.
• Internal automation scripts call the same gateway using API keys with limited scopes.

This lets you support both human users and automation without two entirely separate stacks.

Are API keys still safe to use in 2024–2025?

They can be, if you:

• Use HTTPS everywhere.
• Store keys securely (not in source code or client-side JavaScript).
• Rotate them regularly and on incident.
• Combine them with IP allowlists, rate limits, and monitoring.

For high-risk, user-facing APIs, examples of top 3 examples of authentication methods for APIs increasingly favor OAuth 2.0 and JWTs instead of raw API keys.

How do I choose between JWT and opaque tokens for my API?

Use JWTs when you want stateless verification and rich claims, and you’re ready to manage key rotation and token lifetimes. Use opaque tokens (random strings validated by an introspection endpoint) when you prefer centralized control and easier revocation. Many OAuth servers support both, so you can pilot JWTs internally while keeping opaque tokens for external clients.

If you remember nothing else, remember this: the best examples of top 3 examples of authentication methods for APIs are less about picking a trendy acronym and more about matching risk, architecture, and developer experience. Start simple, layer your defenses, and let your authentication strategy evolve with your system—not the other way around.