API Authentication and Authorization: 6 Methods and Tips for Success

API authentication and authorization is the user management process of verifying the identity of a user or application that is requesting access to an API. API authentication is the process of verifying the identity of the user or application making the request, while API authorization is the process of verifying that the authenticated user or application has permission to access the requested resources.

API authentication can be performed using various methods, such as providing a username and password, or using a token-based system such as OAuth or JWT. API authorization is typically performed using access tokens, which are issued to the client upon successful authentication and can be used to access specific resources for a limited period of time.

The purpose of API authentication and authorization is to ensure that only authorized users or applications are able to access the API and the resources it provides. This helps to protect sensitive data, and ensures that the API is used in a manner that is consistent with its intended purpose.

Why Are API Authentication and Authorization Important? 

API authentication and authorization are important for several reasons:

  • Data security: By requiring authentication and authorization, APIs can ensure that only authorized users or applications are able to access sensitive data. This helps protect sensitive data from unauthorized access, theft, or misuse.
  • User privacy: By requiring authentication and authorization, APIs can ensure that users’ data is only accessed with their permission. This helps to preserve user privacy and to maintain the trust of API users.
  • Resource protection: By requiring authentication and authorization, APIs can ensure that resources are used in a manner that is consistent with their intended purpose. This helps to protect resources from being misused or overused, and to ensure that resources are used in a way that is consistent with the policies of the API provider.
  • Compliance: By requiring authentication and authorization, APIs can help to ensure that they comply with regulations and industry standards for data privacy and security.
  • Improving API security: By requiring authentication and authorization, APIs can make it more difficult for attackers to gain access to sensitive data or to misuse resources. This can help to improve the security of the API and to reduce the risk of security incidents.

6 Common API Authentication and Authorization Methods 

Basic Authentication

Basic authentication is a simple, HTTP-based authentication scheme that allows clients to authenticate with a server by sending a username and password in plain text as part of the HTTP request.

When a client makes a request to a server that requires basic authentication, the server responds with a 401 Unauthorized status code, which indicates that authentication is required. The response also includes a WWW-Authenticate header that specifies that the server is using basic authentication.

To authenticate, the client sends another request to the server with the authorization header, which contains the word “Basic” followed by a base64-encoded string of the username and password separated by a colon. For example, “Authorization: Basic dXNlcm5hbWU6cGFzc3dvcmQ=” represents the credentials “username:password” encoded in base64.

While basic authentication is easy to implement, it has several security limitations. The most significant being that usernames and passwords are sent in plain text, making them susceptible to eavesdropping and man-in-the-middle attacks, amongst others. 

API Key Authentication

API key-based authentication involves sending an API key along with a request. An API key is a unique identifier that is issued by the API provider to authorized users or applications, and is used to identify and track API usage.

To use an API that requires key-based authentication, the user or application includes the API key as a parameter in the request, typically as a query parameter or in a header. The API provider verifies the key and then allows or denies access to the API based on the user’s permissions and the API’s usage limits.

API key-based authentication provides a more secure and scalable alternative to basic authentication, since the API key can be easily revoked or regenerated if it is compromised, and it allows the API provider to monitor and control access to the API more granularly.

However, API key-based authentication has some limitations. For example, if an API key is compromised, an attacker can gain access to the API until the key is revoked. Additionally, API keys can be difficult to manage and distribute in large-scale environments.

TLS Encryption

TLS (Transport Layer Security) encryption is a secure method of authentication that involves encrypting the communication between a client and a server using the TLS protocol, which provides secure communication over a network by encrypting data in transit and providing authentication of the server and client.

A client initiates a secure connection with a server by sending a request to establish a TLS session. The server responds by sending its public key to the client, which uses the key to encrypt a session key that will be used to encrypt all subsequent communication between the client and server.

Once the TLS session is established, the client and server can authenticate each other using digital certificates. The server presents its certificate to the client, which verifies that the certificate was issued by a trusted certificate authority and that the certificate matches the hostname of the server. The client can also present its own certificate to the server for authentication.

TLS-based authentication provides a high level of security and is widely supported by web browsers and web servers. Mutual TLS, also known as mTLS, is a form of TLS authentication in which both the client and the server present and verify digital certificates.

OAuth 2.0

OAuth 2.0 is an authorization framework that allows users or applications to access resources from an API without giving the API access to their credentials, such as a username and password. It is widely used to grant third-party applications access to resources on behalf of a user, without requiring the user to disclose their credentials to the third party.

OAuth 2.0 involves several roles, including the resource owner, the client, the authorization server, and the resource server. The client requests authorization from the resource owner to access resources on the resource server, which is authenticated by the authorization server. If authorization is granted, the client receives an access token that it can use to access the resources.

OAuth 2.0 is widely used by social media platforms, cloud service providers, and other web applications to provide a secure and standardized way of granting access to resources. It offers several security advantages over traditional authentication schemes, including the ability to revoke access to a specific application or user, the ability to grant limited access to specific resources, and the ability to delegate authentication to a trusted third party.

JWT-Based Authentication

JWTs (JSON Web Tokens) are a compact and URL-safe means of representing claims to be transferred between parties. JWTs consist of three parts separated by dots: a header, a payload, and a signature. The header specifies the algorithm used to sign the token, the payload contains the claims, and the signature is used to verify the integrity of the token.

JWTs are often used for authentication and authorization in web applications. When a user logs in, the server generates a JWT that contains information about the user, such as the user ID and permissions. The JWT is then signed using a secret key that only the server knows. The server sends the JWT to the client, which can then use it to access protected resources on the server.

When the client sends a request to the server, it includes the JWT in an authorization header. The server verifies the signature of the JWT using the secret key, and if the signature is valid, it extracts the claims and uses them to authorize the request.

JWTs are widely used in REST APIs, as they allow the stateless transmission of authentication and authorization data between the client and the server. They are also portable, since they can be easily shared between different services and systems.


OpenID Connect (OIDC) is an authentication protocol that extends the OAuth 2.0 framework by providing an identity layer on top of it. OIDC enables users to authenticate with a web application using an identity provider, such as Google or Facebook.

OIDC provides a mechanism for requesting specific user information, such as name or email address, and allows users to grant or deny access to this information. This enables applications to tailor the user experience based on the user’s identity and preferences.

OIDC is widely used in web applications and single sign-on (SSO) systems to provide secure and easy-to-use authentication for users. It is supported by a wide range of identity providers and is built on top of existing web standards, making it easy to integrate into existing systems.

API Authentication and Authorization Best Practices 

Here are some best practices for ensuring secure, manageable authentication and authorization.

Configure Multiple API Keys

Create multiple API keys with different levels of access to the API, rather than using a single API key for all users or applications. If each API key has different permissions, API providers can control the level of access that each user or application has to the API. This provides a more granular and secure approach to authentication, as it allows the API provider to restrict access to certain resources or actions based on the user’s role or level of access.

For example, an API provider might create an API key with read-only access to certain resources for a reporting application, while creating another API key with full access to all resources for an internal application. 

Let the Application and Business Logic Handle Authorization 

This approach involves the defining of authorization rules based on the application’s business logic and using them to determine whether a user or application is authorized to access a resource or perform an action. By allowing the application and business logic to handle authorization, API providers can implement fine-grained control over access to resources, while also making it easier to maintain and update the authorization rules. This approach is more efficient than adding logic to the authorization system. 

For example, an eCommerce application might define authorization rules that allow only authenticated users to access their purchase history, while restricting access to other users. The application could also define rules that restrict access to certain resources based on the user’s role, such as allowing only administrators to manage user accounts. 

Implement OAuth2 in Stateful or Stateless Modes

OAuth2 can be implemented in either a stateful or stateless mode to provide a secure and efficient way of granting access to resources. Stateful modes involve storing the user’s authentication state on the server, while stateless modes involve passing the state with the request.

Stateful mode is more secure, as it prevents unauthorized access to the user’s authentication state. However, it can also be less efficient, as it requires the server to store and manage user sessions.

Stateless mode, on the other hand, is more efficient and scalable, as it allows the server to process requests without the need for session management. However, it also requires additional security measures, such as the use of secure tokens and encrypted communications, to prevent unauthorized access to the user’s state.

Combine OAuth2 and OIDC for SSO 

SSO (Single Sign-On) can be implemented using OAuth2 and OIDC to provide a secure and user-friendly way of authenticating users across multiple applications and services. OAuth2 provides the authorization framework, while OIDC provides the identity layer on top of it.

By implementing SSO using OAuth2 and OIDC, users can authenticate once with an identity provider, and then access multiple applications and services without having to re-enter their credentials. This improves the user experience, while also reducing the risk of credential theft or misuse.

OAuth2 and OIDC also provide a standardized and secure way of exchanging user information and authentication data between applications and services. This allows applications to share user data and provide a more personalized experience, while also ensuring that user data is protected and controlled.

Authentication and Authorization with Frontegg

The industry standard today is to use Authentication providers to “build the door”, but what about Authorization (the door knob)? Most authentication vendors don’t go that extra mile, forcing SaaS vendors to invest in expensive in-house development or outsource this work to external agencies. This often delays investment in core technology development, which negatively impacts innovation, hampers productivity, and time-to-market (TTM) metrics. 

Frontegg’s end-to-end user management platform allows you to authenticate and authorize users with just a few clicks, all via a centralized dashboard that allows seamless role and permission management. Integration also takes just a few minutes, thanks to its plug-and-play nature. It’s also multi-tenant by design. 


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