Need to secure your API? Here's a breakdown of the **top 7 authentication
methods**, their use cases, and strengths:

1. [**OAuth 2.0**](#1-oauth-20): Ideal for third-party integrations. Uses tokens
   for secure, delegated access.
2. [**API Keys**](#2-api-keys): Simple and easy for internal services but less
   secure without proper management.
3. [**JWT (JSON Web Tokens)**](#3-jwt-json-web-tokens): Stateless and efficient
   for microservices and distributed systems.
4. [**Basic Authentication**](#4-basic-authentication): Outdated but simple.
   Best for low-security internal systems.
5. [**Bearer Authentication**](#5-http-bearer-authentication): Token-based,
   modern, and scalable for web APIs.
6. [**mTLS (Mutual Transport Layer Security)**](#6-mtls-mutual-transport-layer-security):
   High-security method using certificates for mutual verification.
7. [**OpenID Connect**](#7-openid-connect): Built on OAuth 2.0, adds identity
   verification for managing user identities.

## Quick Comparison Table

| **Method**            | **Best Use Case**                | **Key Strength**                          | **Limitations**                              |
| --------------------- | -------------------------------- | ----------------------------------------- | -------------------------------------------- |
| OAuth 2.0             | Third-party integrations         | Fine-grained access control               | Complex setup, resource-heavy                |
| API Keys              | Internal services or Public APIs | Easy to implement                         | Limited security, no expiration              |
| JWT                   | Microservices                    | Stateless, fast performance               | No revocation, large token size              |
| Basic Authentication  | Legacy systems                   | Simple setup                              | High security risk, relies on HTTPS          |
| Bearer Authentication | Modern web APIs                  | Token-based, scalable                     | Requires token management                    |
| mTLS                  | High-security systems            | Mutual authentication with certificates   | Complex certificate management               |
| OpenID Connect        | Identity management              | Combines authentication and authorization | Steep learning curve, detailed configuration |

## Choosing the Right Method

- **High Security?** Use OAuth 2.0 or mTLS.
- **Scalability?** JWT or Bearer Authentication.
- **Simplicity?** API Keys or Basic Authentication.
- **Identity Management?** OpenID Connect.
- **Developer Experience?** API Keys.

Read on to dive deeper into how each method works, their pros/cons, and when to
use them.

## Overview of API Authentication Methods

[API authentication](/learning-center/api-authentication) ensures that sensitive
data remains secure by confirming the identity of users or applications
accessing an API.

Here's a quick video overview of the different methods, in case you prefer to
watch instead of reading.

<CalloutVideo
  variant="card"
  title="API Authentication: JWT, OAuth2, and More"
  description="A comprehensive overview of the top API authentication methods, their use cases, and when to use each one."
  videoUrl="https://www.youtube.com/watch?v=xJA8tP74KD0"
  thumbnailUrl="http://i3.ytimg.com/vi/xJA8tP74KD0/hqdefault.jpg"
  duration="6:11"
/>

Today's APIs rely on various authentication methods tailored to different
security and operational needs. Below are seven widely used methods, along with
their main features:

| Authentication Method | Primary Use Case         | Key Characteristic                           |
| --------------------- | ------------------------ | -------------------------------------------- |
| OAuth 2.0             | Third-party integrations | Allows access without sharing passwords      |
| API Keys              | Internal services        | Simple token-based access mechanism          |
| JWT                   | Microservices            | Self-contained, stateless authentication     |
| Basic Auth            | Legacy systems           | Sends username and password in headers       |
| Bearer Auth           | Modern web APIs          | Token-based access via headers               |
| mTLS                  | High-security systems    | Uses certificates for mutual verification    |
| OpenID Connect        | Identity management      | Builds on OAuth 2.0 with identity validation |

When choosing an authentication method, consider these factors:

- **Security Needs**: Basic authentication might suffice for internal tools,
  while mTLS is better for highly sensitive operations.
- **Ease of Implementation**: API keys are straightforward, while OAuth can be
  more complex to set up.
- **Performance**: Lightweight options like JWT are ideal for
  [high-performance systems](/learning-center/increase-api-performance), whereas
  methods like mTLS can demand more resources.
- **Scalability**: Stateless methods like JWT work well for large-scale
  deployments, while stateful methods might face limitations.

With this overview in mind, let's dive deeper into each method, examining how
they work, their advantages, and their limitations.

## 1\. OAuth 2.0

OAuth 2.0 is a widely used protocol for secure API authorization. It uses tokens
to manage and control access to resources, making it a go-to choice for handling
third-party integrations while prioritizing security.

| **OAuth 2.0 Component** | **Purpose**               | **Security Advantage**                          |
| ----------------------- | ------------------------- | ----------------------------------------------- |
| Access Tokens           | Short-term API access     | Reduces risk of credential leaks                |
| Scopes                  | Permission definitions    | Limits access to specific areas                 |
| Authorization Grants    | Token acquisition methods | Supports multiple authentication flows          |
| Refresh Tokens          | Long-term access          | Reduces the need for frequent re-authentication |

OAuth 2.0 uses _scopes_ to specify and restrict application permissions. For
example, when connecting to a social media platform, an app might request
permissions like "read profile" or "post updates" to ensure only necessary
access is granted [\[5\]](https://auth0.com/intro-to-iam/what-is-oauth-2).

### OAuth 2.0 Implementation Tips

To implement OAuth 2.0 securely, follow these guidelines:

- Always use HTTPS to secure communication.
- Validate tokens to ensure they're legitimate.
- Store credentials securely to avoid unauthorized access.
- Set appropriate expiration times for tokens to balance usability and security.

OAuth 2.0 aligns well with GDPR compliance by empowering users to control data
access and revoke permissions whenever necessary
[\[5\]](https://auth0.com/intro-to-iam/what-is-oauth-2)[\[4\]](https://www.netlify.com/learning-center/api-authentication-methods/).
Its token-based system is efficient for managing large-scale user bases and
applications, making it ideal for scenarios like social media integrations or
ecosystems with multiple apps
[\[5\]](https://auth0.com/intro-to-iam/what-is-oauth-2)[\[4\]](https://www.netlify.com/learning-center/api-authentication-methods/).

Here's an interview we did with Curity on how to build a privacy-preserving API
authentication system on top of OAuth:

<CalloutVideo
  variant="card"
  title="OAuth + Privacy Preservation with Curity"
  description="Learn how to build a privacy-preserving API authentication system on top of OAuth."
  videoUrl="https://www.youtube.com/watch?v=URPQSenWerE"
  thumbnailUrl="http://i3.ytimg.com/vi/URPQSenWerE/hqdefault.jpg"
  duration="21:49"
/>

Although it requires more setup compared to simpler methods like API Keys, OAuth
2.0 delivers enhanced security and scalability. For internal applications with
fewer security demands or a public API where developer experience is paramount,
API Keys may be a better option.

<CalloutDoc
  title="Auth0 JWT Authentication Policy"
  description={`Zuplo's Auth0 JWT Authentication policy validates JWTs issued by Auth0, making it easy to secure your API with OAuth 2.0 token-based authentication.`}
  href="https://zuplo.com/docs/policies/auth0-jwt-auth-inbound"
  features={[
    `Token-based access`,
    `Scope validation`,
    `Automatic key rotation`,
  ]}
/>

## 2\. API Keys

[API Keys](/learning-center/api-key-authentication) are simple, unique strings
used to validate API requests. Unlike OAuth 2.0, which offers more advanced
control and scalability,
[API Keys focus on simplicity](/blog/you-should-be-using-api-keys). However,
this simplicity comes with the need for careful security management.

| **Implementation Aspect** | **Details**                            | **Security Consideration**               |
| ------------------------- | -------------------------------------- | ---------------------------------------- |
| Basic Setup               | Single unique string in request header | Must be transmitted over HTTPS           |
| Key Management            | Individual keys per consumer           | Regular rotation required                |
| Access Control            | Limited permission options             | Best for straightforward access patterns |
| Scalability               | Manual key distribution and tracking   | Can become complex with many users       |

Some would say API Keys work well in low-risk, controlled environments, such as
internal development setups or trusted B2B integrations. At Zuplo, we argue that
[API keys are the best choice for public facing APIs](/learning-center/rebuttal-api-keys-can-do-everything).

### Securing API Keys

To keep API Keys secure, follow these steps:

- Always transmit API Keys over HTTPS to avoid interception.
- Rotate keys regularly to reduce the risk of exposure.
- Monitor API usage for any signs of unauthorized access.
- Become a [Github secret scanning](/blog/api-key-leak-prevention-announcement)
  partner like Zuplo to keep users and you in the loop on leakages.

<CalloutVideo
  variant="card"
  title="API Key Authentication Best Practices"
  description="Learn the best practices for implementing secure API key authentication in your APIs."
  videoUrl="https://www.youtube.com/watch?v=ooyOmiczY1g"
  thumbnailUrl="http://i3.ytimg.com/vi/ooyOmiczY1g/hqdefault.jpg"
  duration="25:55"
/>

When using API Keys in production environments:

- **Store keys securely** to prevent unauthorized access.
- **Apply access controls** to limit permissions based on usage needs.
- **Monitor and audit usage** to detect anomalies and ensure compliance.
- **Rotate keys periodically** to maintain security standards.

While API Keys lack the advanced features of OAuth 2.0, they are still useful
for specific scenarios
[\[2\]](https://www.hallme.com/blog/pros-and-cons-of-the-most-popular-api-authentication-methods/)[\[4\]](https://www.netlify.com/learning-center/api-authentication-methods/).
Their success depends on proper implementation and a clear understanding of
their limitations.

If you'd like to implement API key authentication easily and fast -
[check out our offering](https://zuplo.com/features/api-key-management?utm_source=blog).
For developers looking for a stateless and scalable solution, JWT might be a
better fit, which we'll discuss next.

<CalloutDoc
  title="API Key Authentication Policy"
  description={`Zuplo's API Key Authentication policy validates API keys against your configured key store, providing simple yet powerful authentication for your APIs.`}
  href="https://zuplo.com/docs/policies/api-key-inbound"
  features={[
    `Self-serve API keys`,
    `Rate limiting and quotas`,
    `Secret scanning
integration`,
  ]}
/>

## 3\. JWT (JSON Web Tokens)

[JWTs](/learning-center/jwt-vs-api-key-authentication) are compact tokens that
securely carry authentication data. They are designed to balance ease of
implementation with strong security features.

| **Feature**          | **Implementation**            | **Security Impact**                             |
| -------------------- | ----------------------------- | ----------------------------------------------- |
| **Token Structure**  | Encoded JSON in Base64 format | Includes claims and cryptographic signatures    |
| **State Management** | Stateless setup               | Lowers server load and reduces database queries |
| **Validation**       | Cryptographic signing         | Ensures tokens can't be tampered with           |
| **Expiration**       | Adjustable time limits        | Reduces risk from compromised tokens            |

### How JWTs Work

JWTs simplify authentication by removing the need for repeated backend calls.
This makes them a great fit for distributed systems and microservices, where
scalability and performance are key. Their stateless nature ensures they work
efficiently in environments with high demand. Check out
[our guide to implementing JWT auth with Auth0](/blog/jwt-authentication-with-auth0)
to get started with JWTs. If you're a Supabase fan, also watch
[our Supabase JWT API authentication guide](/blog/api-authentication-with-supabase-jwt).
Here's a video tutorial if you're tired of reading:

<CalloutVideo
  variant="card"
  title="JWT Authentication Tutorial"
  description="A step-by-step guide to implementing JWT authentication for your APIs."
  videoUrl="https://www.youtube.com/watch?v=UEeSZkV7o_Y"
  thumbnailUrl="http://i3.ytimg.com/vi/UEeSZkV7o_Y/hqdefault.jpg"
  duration="7:28"
/>

### JWT Security Considerations

While JWTs are effective, their design comes with specific security
responsibilities:

1. Store tokens securely and use expiration and refresh mechanisms to limit
   potential risks.
2. Always verify token signatures and claims for every request to ensure
   authenticity.

To make the most out of JWTs while keeping them secure:

- Sign tokens using robust encryption algorithms.
- Keep the token payload as small as possible for better performance.
- Securely store secret keys on the server to prevent breaches.

JWTs are widely used for stateless authentication in microservices, cutting down
on database dependency and boosting system performance
[\[1\]](https://blog.hubspot.com/website/api-authentication)[\[3\]](https://cloud.google.com/api-gateway/docs/authenticating-users-jwt).
Their self-contained nature eliminates the need for session storage, which is
especially beneficial in distributed systems.

<CalloutDoc
  title="OpenID JWT Authentication Policy"
  description={`Zuplo's OpenID JWT Authentication policy validates JWTs from any OpenID Connect compliant identity provider using JWKS for signature verification.`}
  href="https://zuplo.com/docs/policies/open-id-jwt-auth-inbound"
  features={[
    `Signature verification`,
    `Automatic key rotation`,
    `Claims
validation`,
  ]}
/>

Although JWTs are excellent for authentication, OAuth 2.0 builds on this by
offering more advanced authorization workflows, which will be covered next.

## 4\. Basic Authentication

[Basic Authentication](/learning-center/simple-api-authentication) is a
straightforward method for API authentication, relying on a username and
password combination sent through HTTP headers. Unlike OAuth 2.0 or JWT, it
doesn't use token-based mechanisms, making it less ideal for systems that need
high security or scalability.

| Feature                | Implementation                                | Security Impact                       |
| ---------------------- | --------------------------------------------- | ------------------------------------- |
| **Credential Format**  | Base64 encoded username:password              | Can be decoded easily if intercepted  |
| **Transport Security** | Requires HTTPS                                | Critical to prevent potential attacks |
| **Session Management** | Stateful - credentials sent with each request | Adds load to servers and networks     |

### When to Use Basic Auth

The security of Basic Authentication hinges entirely on HTTPS to protect
credentials. Its simplicity makes it a good fit for:

- Internal development, testing, and debugging setups
- Older systems that need compatibility with existing methods
- APIs with low-security requirements

To use Basic Authentication securely, follow these guidelines:

- **Always use HTTPS** to encrypt credentials and prevent interception.
- **Restrict access** to non-sensitive resources to minimize risks.
- **Rotate passwords** regularly to reduce exposure in case of compromise.
- **Implement rate limiting** to defend against brute force attacks.

Since Basic Authentication requires credentials to be validated with every
request, it increases server and network load, which can be a problem in
environments with high traffic. While it's easy to set up, it often doesn't meet
modern security or compliance standards
[\[1\]](https://blog.hubspot.com/website/api-authentication).

This simplicity makes it useful for certain scenarios, but most modern
applications need stronger authentication methods that balance security and
implementation effort
[\[2\]](https://www.hallme.com/blog/pros-and-cons-of-the-most-popular-api-authentication-methods/).

<CalloutDoc
  title="Basic Auth Policy"
  description={`Zuplo's Basic Auth policy authenticates incoming requests using the Basic authentication standard, with support for multiple accounts and custom user data.`}
  href="https://zuplo.com/docs/policies/basic-auth-inbound"
  features={[
    `Multiple account support`,
    `Custom user data payloads`,
    `Environment variable credential storage`,
  ]}
/>

Next, we'll dive into HTTP Bearer Authentication, a method that offers improved
security and scalability.

## 5\. HTTP Bearer Authentication

Bearer Authentication is a step up from Basic Authentication, relying on
token-based security for better protection and flexibility. It's a popular
choice for modern APIs due to its simplicity and ability to handle high traffic
efficiently.

### Token Management and Security

Bearer Authentication revolves around the use of tokens. Here's a breakdown of
its key components:

| Component            | Details                                                        | Security Notes                                    |
| -------------------- | -------------------------------------------------------------- | ------------------------------------------------- |
| **Token Format**     | A unique access token sent in the Authorization header         | Must use cryptographic methods to ensure security |
| **Transport Layer**  | Requires HTTPS for safe communication                          | Prevents token interception during transmission   |
| **Validation**       | The server checks the token's validity with every request      | Minimizes the risk of exposing user credentials   |
| **Token Management** | Includes secure creation, expiration, and revocation processes | Needs strict oversight to avoid misuse            |

Thanks to its stateless design, Bearer Authentication doesn't store user
credentials for every request. This makes token validation quick and efficient,
especially in distributed systems or high-traffic environments. It's a solid
choice for APIs that need to scale horizontally without sacrificing speed.

Implementing Bearer Authentication securely means addressing several layers of
protection:

- Using strong cryptographic methods for token creation
- Setting automatic expiration times for tokens
- Ensuring compromised tokens can be revoked immediately
- Regularly rotating tokens and securely disposing of expired ones
- Monitoring token activity for unusual patterns

Organizations can combine Bearer Authentication with other security techniques
to strengthen their defenses. This layered approach allows for customization
based on specific needs.

While Bearer Authentication offers a strong balance of performance and security,
technologies like mTLS provide even greater trust by enabling mutual
verification.

<CalloutDoc
  title="JWT Auth Policy"
  description={`Zuplo's OpenID JWT Authentication policy validates bearer tokens from any OpenID-compliant provider for flexible token-based authentication.`}
  href="https://zuplo.com/docs/policies/open-id-jwt-auth-inbound"
  features={[
    `Universal provider support`,
    `Token signature validation`,
    `Flexible
claims access`,
  ]}
/>

## 6\. mTLS (Mutual Transport Layer Security)

Mutual Transport Layer Security (mTLS) offers a robust approach to API
authentication by requiring both the client and server to verify each other
using digital certificates. This two-way verification ensures a highly secure
communication channel.

### Certificate-Based Trust

mTLS relies on a structured certificate exchange process to establish trust:

| Component                 | Function                       | Security Advantage                 |
| ------------------------- | ------------------------------ | ---------------------------------- |
| **Client Certificate**    | Confirms the client's identity | Blocks unauthorized access         |
| **Server Certificate**    | Verifies the server's identity | Prevents man-in-the-middle attacks |
| **Certificate Authority** | Validates certificates         | Ensures certificates are authentic |
| **TLS Handshake**         | Encrypts communication         | Safeguards data during transfer    |

Zuplo offers an easy way to implement mTLS by allowing developers to add an
[mTLS inbound policy](https://zuplo.com/docs/policies/mtls-auth-inbound).
Industries handling sensitive data, such as finance, healthcare, and government,
frequently use mTLS to protect critical information during exchanges.

### mTLS Challenges and Recommendations

While mTLS provides a high level of security, it does come with some trade-offs.
Setting up the necessary infrastructure for certificate management can be
complex. Additionally, the initial connection may take longer due to the
verification process. Automating certificate renewals and revocations is
essential to reduce manual overhead.

For effective mTLS implementation:

- **Automate Certificate Management** — Use tools to handle certificate
  rotation, expiration monitoring, and revocation automatically. This reduces
  administrative burden and minimizes errors.
- **Improve Performance** — Cache validated certificates to speed up future
  connections and optimize session timeouts. Efficient validation methods can
  also help streamline the process.
- **Maintain Strong Security** — Regularly update certificate authorities to
  guard against misuse. Implement robust revocation mechanisms to address
  compromised certificates quickly.

Although mTLS offers a high-security option, it may not always be the best fit
for every scenario. For applications where simplicity and scalability are more
critical, alternatives like OpenID Connect, which builds on OAuth 2.0, might be
a better choice. However, for environments requiring maximum trust, mTLS remains
a top contender.

<CalloutDoc
  title="mTLS Authentication Policy"
  description={`Zuplo's mTLS Authentication policy enables mutual TLS authentication, requiring clients to present valid certificates for API access.`}
  href="https://zuplo.com/docs/policies/mtls-auth-inbound"
  features={[
    `Certificate-based auth`,
    `Client certificate validation`,
    `CA
support`,
  ]}
/>

## 7\. OpenID Connect

OpenID Connect builds on OAuth 2.0 by adding an identity layer, making it a
go-to choice for applications that need both authentication and authorization.
Developed by the [OpenID Foundation](https://openid.net/), it's widely used by
major players like Google, Microsoft, and Amazon.

### Core Components

| Component        | Purpose                          | Security Benefit                  |
| ---------------- | -------------------------------- | --------------------------------- |
| Identity Layer   | Verifies and authenticates users | Blocks unauthorized access        |
| JWT Integration  | Secures identity data transfer   | Protects data integrity           |
| Single Sign-On   | Centralized access to services   | Simplifies credential management  |
| Token Validation | Confirms identity claims         | Guards against token manipulation |

Google's authentication system is a prime example of OpenID Connect in action.
It allows users to access services like
[Gmail](https://www.google.com/gmail/about/), Drive, and Calendar without
logging in repeatedly. Unlike simpler methods such as API Keys, OpenID Connect
offers a stronger framework for both authentication and authorization.

### OpenID Connect Implementation Tips

Its stateless design boosts scalability and minimizes risks like phishing. To
implement OpenID Connect effectively:

- **Token Management**: Validate JWTs and store tokens securely to avoid common
  security flaws.
- **Identity Provider Choice**: Select providers that align with compliance
  standards and user requirements.
- Validate tokens thoroughly, including signatures and claims.
- Set appropriate expiration times for tokens.
- Use HTTPS for all authentication flows to maintain secure communication.
- Keep client libraries and dependencies up to date.
- Monitor authentication activity for unusual behavior.

OpenID Connect bridges the gap between authentication and secure API access,
offering a reliable option for modern applications. Its ability to streamline
identity verification while enhancing security makes it a strong choice for
developers.

<CalloutDoc
  title="OpenID JWT Authentication Policy"
  description={`Zuplo's OpenID JWT Authentication policy validates tokens from any OpenID Connect compliant provider, enabling seamless SSO and identity management.`}
  href="https://zuplo.com/docs/policies/open-id-jwt-auth-inbound"
  features={[
    `Auth0, Okta, and others`,
    `OIDC discovery support`,
    `Claims-based
authorization`,
  ]}
/>

## Pros and Cons

This table outlines the strengths and weaknesses of various authentication
methods, helping developers choose the right approach for their projects.

| Authentication Method | Advantages                                                                             | Disadvantages                                                                   | Best Use Cases                                                |
| --------------------- | -------------------------------------------------------------------------------------- | ------------------------------------------------------------------------------- | ------------------------------------------------------------- |
| OAuth 2.0             | • Token-based security • Fine-grained access control • Supports selective data sharing | • Complex setup • Higher resource demands • Increased overhead                  | Enterprise apps requiring delegated access                    |
| API Keys              | • Easy to set up • Straightforward management • Ideal for server-to-server use         | • Limited security • No expiration • Vulnerable to key exposure                 | Internal APIs or DevX Focused Public APIs                     |
| JWT                   | • Stateless and self-contained tokens • Reduces server load • Quick performance        | • Large token size • No revocation mechanism • Validation can be tricky         | Microservices and distributed systems                         |
| Basic Authentication  | • Simple to implement • Broad compatibility • Minimal overhead                         | • Credentials sent in plain text • No access control • High security risk       | Testing and development purposes only                         |
| HTTP Bearer           | • More secure than Basic Auth • Easy to implement • Token-based approach               | • Requires token management • Lacks built-in validation • Limited functionality | APIs with moderate security demands                           |
| mTLS                  | • Encrypted communication • Mutual authentication • High level of security             | • Complex certificate management • Higher costs • Performance impact            | Financial and healthcare APIs                                 |
| OpenID Connect        | • Adds an identity layer • Supports Single Sign-On • Strong security features          | • Challenging setup • Requires detailed configuration • Steep learning curve    | Applications needing authentication and identity verification |

Security should always be a top priority when choosing an authentication method.
OAuth 2.0 and OpenID Connect offer advanced security features, while Basic
Authentication provides minimal protection and is better suited for low-risk
scenarios.

JWT stands out for its performance benefits, as it eliminates the need for
repeated API calls to fetch user data or permissions. This makes it a strong
choice for high-traffic APIs
[\[3\]](https://cloud.google.com/api-gateway/docs/authenticating-users-jwt)[\[4\]](https://www.netlify.com/learning-center/api-authentication-methods/).

API Keys are simple to implement but fall short in high-security environments
due to the risk of key exposure
[\[1\]](https://blog.hubspot.com/website/api-authentication). Developers should
weigh their project's needs against the available resources and expertise.

## OAuth 2.0 Platform Support Matrix

Choosing the right API management platform for OAuth 2.0 can significantly
impact your implementation timeline and ongoing maintenance burden. Here's how
the major platforms stack up for OAuth 2.0 support and token validation:

| Platform        | OAuth 2.0 Support              | Token Validation                  | OIDC/JWKS           | Custom IdP Integration       | Complexity          |
| --------------- | ------------------------------ | --------------------------------- | ------------------- | ---------------------------- | ------------------- |
| Zuplo           | Built-in JWT validation policy | Automatic JWKS refresh            | Native OIDC support | Auth0, Okta, Clerk, Supabase | Low — JSON config   |
| Apigee          | OAuthV2 policy                 | Manual key config                 | VerifyJWT policy    | Custom integration required  | High — XML policies |
| AWS API Gateway | Cognito + Lambda authorizer    | Cognito native, custom via Lambda | Via Cognito         | Cognito or custom Lambda     | Medium              |
| Kong            | OpenID Connect plugin          | Plugin-based                      | OIDC plugin         | Via plugin configuration     | Medium              |
| Tyk             | Built-in OAuth middleware      | JWT validation included           | OIDC support        | Multiple IdP support         | Medium              |

What stands out here is the difference in configuration complexity. With Zuplo,
adding OAuth 2.0 authentication to your API is a matter of adding a JSON policy
configuration — you specify your identity provider's issuer URL, the expected
audience, and you're done. The gateway handles JWKS key fetching, caching, and
automatic rotation behind the scenes. Most competing platforms require either
verbose XML policy definitions (Apigee), custom code in Lambda functions (AWS),
or plugin configuration that still requires understanding the platform's
middleware pipeline. For teams that want to ship secure APIs quickly without
becoming experts in gateway-specific configuration languages, this difference in
developer experience is significant.

## TypeScript-First Authentication Policies

While declarative JSON policies handle the majority of authentication use cases,
Zuplo makes it easy to use custom logic when needed such as handling
multi-tenant validation, dynamic claim enrichment, or integration with internal
authorization services. Zuplo's TypeScript-first approach lets you write custom
authentication policies with full programmatic control:

```typescript
import { ZuploContext, ZuploRequest, HttpProblems } from "@zuplo/runtime";

export default async function authPolicy(
  request: ZuploRequest,
  context: ZuploContext,
) {
  // Custom claim validation
  const claims = request.user.data;

  // Enforce organization-level access
  if (!claims?.org_id) {
    return HttpProblems.forbidden(request, context, {
      detail: "Organization claim required",
    });
  }

  return request;
}
```

This TypeScript-first approach gives you full programmatic control over your
authentication logic — something that's particularly valuable for enterprise
scenarios. You can enforce multi-tenant access rules by validating organization
claims, implement custom role-based access control by inspecting JWT roles, or
enrich requests with authentication context that downstream services need. Since
these policies run at the gateway level, your backend services receive
pre-validated, context-enriched requests without having to duplicate
authentication logic across every microservice.

## Authentication for AI and LLM Integrations

As AI agents and large language models become integral parts of application
architectures, the same authentication principles that protect traditional APIs
apply to AI-to-API communication — and in some cases, they matter even more.

AI agents that call external APIs need credentials just like any other client.
Whether an LLM-powered assistant is fetching customer data, triggering
workflows, or querying internal services, it authenticates using the same
methods covered in this article: API keys for straightforward access, OAuth 2.0
tokens for scoped authorization, or JWTs for stateless validation in distributed
systems. The difference is that AI agents may make requests at higher volumes
and with less human oversight, which raises the stakes for proper authentication
and access control.

[MCP (Model Context Protocol)](https://zuplo.com/docs/handlers/mcp-server)
servers present a newer challenge. MCP servers expose APIs specifically for AI
agents to consume, and they need the same robust security posture as any
public-facing API. Without proper authentication, an MCP server could become an
unmonitored entry point into your infrastructure.

Key considerations for AI authentication include:

- **Agent credential provisioning**: Each AI agent or service should have its
  own credentials — never share API keys across agents or embed them in prompts.
- **Per-agent rate limits**: AI agents can generate request volumes that
  overwhelm backend services. Apply rate limiting per credential to prevent
  runaway agents from causing outages.
- **Audit logging**: Every AI-initiated request should be traceable. Log which
  agent made the call, what credentials it used, and what resources it accessed.

Zuplo's [MCP Gateway](/docs/handlers/mcp-server) handles authentication
automatically when exposing your APIs to AI agents, applying the same JWT
validation, API key management, and rate limiting policies you already use for
human consumers. This means you can secure AI-to-API traffic without building a
separate authentication layer — the same policies protect all your consumers,
whether they're developers, end users, or AI agents.

## Implementing Authentication with Zuplo

The best API authentication method depends entirely on your specific needs. Each
option shines in particular scenarios, offering tailored benefits.

**API Keys** provide the fastest and easiest developer experience for your
users, but come at the cost of complexity on your side. Many professional APIs
like Stripe use API keys to optimize for user experience and onboarding speed.

**OAuth 2.0** works well for enterprise applications that require delegated
access and robust security. Its popularity highlights its ability to handle
complex authorization requirements effectively
[\[5\]](https://auth0.com/intro-to-iam/what-is-oauth-2).

**JWT** is a great choice for distributed systems where quick token validation
is critical. Its stateless design makes it a natural fit for high-performance
environments
[\[3\]](https://cloud.google.com/api-gateway/docs/authenticating-users-jwt). On
the other hand, **mTLS** is a strong option for industries like finance or
healthcare, where mutual authentication ensures added security, even though it
involves more intricate certificate management.

**OpenID Connect** builds on OAuth 2.0 to streamline user authentication and
identity verification, providing a reliable solution for managing identities
[\[4\]](https://www.netlify.com/learning-center/api-authentication-methods/).

Here's a quick guide to help you decide:

- **Developer Experience**: API Keys
- **High-security needs**: OAuth 2.0 or mTLS
- **Performance-critical systems**: JWT
- **Identity management**: OpenID Connect
- **Internal microservices**: JWT or mTLS

Opting for a robust method like OAuth 2.0 early on can save you from costly
migrations down the road
[\[2\]](https://www.hallme.com/blog/pros-and-cons-of-the-most-popular-api-authentication-methods/).
As APIs become more complex, token-based methods are leading the way in
balancing security and scalability. Matching your authentication strategy to
your system's long-term needs is key to staying ahead
[\[1\]](https://blog.hubspot.com/website/api-authentication).