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What is Bearer Token and How it Works?

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What is Bearer Token and How it Works?

What is Bearer Token? A complete explanation of its details! There are many API authentication methods over HTTP. Bearer Token is one of the most commonly used. In this article, Bearer Token will be fully explained to you.

There are many API authentication methods over HTTP, such as Basic Authentication and Digest Authentication. Among them, Bearer Token is one of the most commonly used. In the following sections, we will delve into a comprehensive exploration of the definition, features, and usage of Bearer Tokens.

Choose Apidog for seamless API protection with versatile authentication options, including the simplicity of Basic Authentication, the flexibility of Bearer tokens, and advanced features like OAuth and JWT. Apidog's intuitive interface makes API security easy, catering to all skill levels, while its scalability ensures robust support as your application grows.

What is Bearer Authorization?

Bearer Authorization is an HTTP authentication scheme commonly used with OAuth 2.0. In this approach, the client includes an access token in the "Authorization" header using the "Bearer" scheme, granting permission to access protected resources. The server validates the token for authorization. It's a widely used method for securing API access, especially in scenarios involving third-party applications.

What is a Bearer Token?

A Bearer token is a type of token used for authentication and authorization and is used in web applications and APIs to hold user credentials and indicate authorization for requests and access.

Generating Bearer tokens based on protocols and specifications such as OAuth and JWT (JSON Web Token). The authenticated user obtains the Bearer token issued by the server and sends it to the server in the header of the request. The server verifies the received bearer token and controls user access based on the token. The Bearer token is also usually sent over an encrypted connection via HTTPS. This prevents unauthorized access by malicious third parties even if the token is stolen.

Composition of the Bearer Token

Bearer tokens are generally composed of a random string of characters. Formally, it takes the form of the "Bearer" keyword and the token value separated by spaces. The following is the general form of a Bearer token:

Bearer {token_value}

Here is an example of an actual Bearer token:

Bearer eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJzdWIiOiIxMjM0NTY3ODkwIiwibmFtZSI6Ikpva

What is Difference Between API Key and Bearer Token?

API keys and Bearer tokens are both mechanisms used to authenticate and authorize access to APIs, but they have key differences in their implementation and use:

Aspect API Key Bearer Token
Format Alphanumeric string Alphanumeric string (may be more complex with additional info)
Usage Passed as a query parameter or in headers Included in the Authorization header using "Bearer" scheme
Scope Typically tied to account/project, predefined access Versatile, supports fine-grained access control, OAuth 2.0 usage
Security Simple to use, but may be less secure if mishandled Generally considered more secure, supports token expiration

API keys are primarily used for authorization. They grant access to specific endpoints or actions within an API. When an API key is provided, it allows the client to perform certain authorized operations based on the permissions associated with that key.

On the other hand, Bearer Tokens are employed for authentication purposes. These tokens authenticate the client and provide access to API resources. Once a client is authenticated using a Bearer Token, it gains permission to interact with the API's resources.

Bearer Token Validity Period

Bearer tokens are typically used as temporary access tokens. The token has a validity period, and when it expires, the user must re-authenticate.

The validity period of a Bearer token is determined by the authentication protocol and server implementation. It can be expressed in absolute time (e.g., 30 minutes from issuance) or relative time (e.g., 24 hours from issuance).

A shorter expiration enhances security but may impact user experience. Setting an appropriate validity period is crucial for security. When sending requests with Bearer tokens, how to pass the token depends on the specific web service or API being accessed.

Advantages and Disadvantages of Bearer Tokens

Bearer tokens have advantages and disadvantages in the context of authentication and authorization.

Advantages of Bearer Tokens:

  1. Simplicity: Bearer tokens are simple to implement and use, making them user-friendly for developers.
  2. Statelessness: Bearer tokens are typically stateless, meaning the server does not need to store token information. This simplifies server-side implementation and scalability.
  3. Versatility: Bearer tokens are versatile and can be used in various authentication scenarios, including single sign-on (SSO) and third-party application access.
  4. Token Revocation: When using a centralized authentication server (e.g., OAuth 2.0), bearer tokens can be easily revoked if compromised or when access needs to be terminated.

Disadvantages of Bearer Tokens:

  1. Security Dependency: Bearer tokens rely heavily on the security of the communication channel (usually HTTPS). If intercepted, they can be misused.
  2. Token Stolen Risks: If a bearer token is leaked or stolen, there is a potential risk as anyone possessing the token can access the associated resources.
  3. Limited Context: Bearer tokens are typically self-contained, providing limited context about the user or the application. Additional queries may be needed to obtain more information.
  4. Token Management: Managing the lifecycle of bearer tokens, including issuing, refreshing, and revoking, requires careful implementation to ensure security.
  5. Scope Concerns: Bearer tokens often have broad access scopes, which might pose a security risk if not appropriately managed, especially in scenarios where fine-grained control is essential.

Next, we will show you how does Bearer Token works and use Apidog, a sophisticated API management tool, to authenticate the Bearer Token, send the request, and get the response.

How Does Bearer Token Work?

The Authentication server creates Bearer Tokens upon user authentication for your application. These tokens, the main access type in OAuth 2.0, essentially mean "Grant access to the bearer of this token."

Bearer Tokens, structured values from the authentication server, are not random and depend on both user and client information.

To access an API, you use an Access Token, which has a short lifespan (around an hour). To get a new Access Token, submit the bearer token and your client ID to the Authentication server. This ensures the bearer token matches the application it was created for.

How to Authenticate Bearer Token in Apidog

When unit testing an API in Apidog, the Bearer Token authentication method is very simple.

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Download the Apidog API management tool here. Perfectly compatible with macOS, Windows, and Linux. Web version is also available.

Open an existing API in Apidog, switch to "Debug" mode, select "Request" > "Auth", specify the type as "Bearer Token", and enter the Token in the input box at the bottom to submit.


It's important to note that bearer tokens should be kept secure and not shared unnecessarily. They should also be periodically rotated or revoked as required for security purposes.