[Guide] What is a cURL Bearer Token?

There are some occasional exceptions where you will need a bearer token for accessing your cURL API. Learn what you need to do to ensure secure bearer token storage and correct implementation for your API!

Steven Ang Cheong Seng

Steven Ang Cheong Seng

14 May 2025

[Guide] What is a cURL Bearer Token?

Authorization plays a pivotal role in regulating access and safeguarding sensitive data. Among the various authorization mechanisms, bearer tokens have emerged as a prevalent approach due to their simplicity and versatility. When employed with cURL, a popular command-line tool for transferring data, bearer tokens offer a streamlined method for incorporating authorization into API requests.

💡
Command-line tools like cURL (Client for URL) can come in the form of commands to make HTTP requests. To convert them into more readable forms, you will need a tool like Apidog.

Quickly get started with APidog to build, test, mock, and document APIs within a single application - no more alt-tabbing to different windows for the sake of app development!

To learn more about Apidog, make sure to click the button below.
Apidog An integrated platform for API design, debugging, development, mock, and testing
REAL API Design-first Development Platform. Design. Debug. Test. Document. Mock. Build APIs Faster & Together.
button

This article delves into the intricacies of cURL bearer tokens, elucidating their core concepts, implementation strategies, and potential benefits. By equipping readers with a comprehensive understanding of this authorization technique, we empower them to leverage cURL's capabilities for seamless and secure API interactions.

To fully grasp the topic of this article, we will first discuss what cURL and bearer tokens are individually.

What is cURL?

cURL, short for "client URL," is a free and open-source software project that provides two powerful tools for interacting with the web:

cURL Command-line Tool

This is the workhorse of cURL and allows users to transfer data using various network protocols directly from a terminal window. Think of it as giving instructions to your computer on how to communicate with a specific location on the internet.

Libcurl Development Library

This underlying library forms the core functionality of cURL. It acts as a set of building blocks that programmers can integrate into their applications for programmatic data transfer.

The beauty of cURL lies in its versatility. It supports a wide range of protocols, including the most commonly used ones like:

HTTP (Hypertext Transfer Protocol)

The foundation of web communication that is used for accessing websites and transferring data.

HTTPS (Secure HTTP)

The encrypted version of HTTP ensures secure communication with websites.

FTP (File Transfer Protocol)

Used for uploading and downloading files between computers.

SFTP (Secure File Transfer Protocol)

Encrypted version of FTP for secure file transfers.

Key Features of the cURL Command-Line Tool

Simple and User-Friendly

Commands are easy to learn and follow, even for beginners.

Flexibility

Offers a vast array of options for customizing data transfers, like specifying headers, setting timeouts, and handling authentication.

Cross-Platform Compatibility

Runs seamlessly on various operating systems like Windows, macOS, and Linux.

Scriptable

Can be integrated into scripts for automating repetitive data transfer tasks.

Common Uses of cURL

While downloading files and testing APIs are popular uses of cURL, its capabilities extend far beyond these basic functions. Here's a closer look at some of the advanced applications of cURL:

Advanced Download Management

Communication and Authentication

Web Scraping (with Caution)

Scripting and Automation

Debugging and Troubleshooting

What are Bearer Tokens?

Bearer tokens are essentially opaque strings of characters, typically alphanumeric or a combination of letters and numbers. It doesn't contain any human-readable information but serves as a unique identifier for an authorized user or application. The server that issues the token is responsible for associating it with specific access rights and permissions.

Typical Workflow of How Bearer Tokens Work

Step 1 - Authentication

The user or application first goes through an authentication process, often using mechanisms like username/password combinations or OAuth [OAuth]. This process verifies the user's identity and determines the level of access they should have.

Step 2 - Token Issuance

Upon successful authentication, the server generates a bearer token. This token encapsulates the user's identity and granted permissions.

Step 3 - Authorization with cURL

When the user or application needs to access a protected resource using cURL, they include the bearer token in the request header. The header typically follows the format "Authorization: Bearer <token>".

Step 4 - Server-Side Validation

The server receiving the cURL request intercepts the authorization header and extracts the bearer token. It then validates the token's authenticity and verifies the user's permissions associated with the token.

Step 5 - Granting Access

If the token is valid, the server grants access to the requested resource based on the permissions encoded within the token. If the token is invalid or expired, access is denied.

Code Examples of cURL with Bearer Tokens

Example 1 - cURL POST Request with Bearer Token

This example demonstrates sending data to a protected resource using a POST request.

# API endpoint for creating a new user
API_URL="https://api.example.com/users"

# Bearer token for authorized user
BEARER_TOKEN="your_bearer_token_here"

# User data in JSON format (replace with your actual data)
USER_DATA='{"name": "John Doe", "email": "john.doe@example.com"}'

curl -X POST \
  -H "Authorization: Bearer ${BEARER_TOKEN}" \
  -H "Content-Type: application/json" \
  -d "${USER_DATA}" \
  ${API_URL}

Code explanation:

Example 2 - cURL with Bearer Token and Query Parameters

This example showcases including query parameters in the URL along with a bearer token.

# API endpoint for fetching users (replace with your actual endpoint)
API_URL="https://api.example.com/users?limit=10&offset=20"

# Bearer token for authorized user
BEARER_TOKEN="your_bearer_token_here"

curl -X GET \
  -H "Authorization: Bearer ${BEARER_TOKEN}" \
  ${API_URL}

Code explanation:

This script uses a GET request with query parameters appended to the URL. These parameters (limit and offset) can be used to control the number of results returned and the starting point for data retrieval.

Apidog - Implement cURL Codes into Readable Requests

Apidog is a powerful, comprehensive API development tool that provides developers with complete tools for the entire API lifecycle. With Apidog, you can build, test, mock, and document APIs within a single application!

apidog interface
button

Import and Edit cURL APIs with Apidog

apidog import curl

Apidog supports users who wish to import cURL commands to Apidog. In an empty project, click the purple + button around the top left portion of the Apidog window, and select Import cURL.

stripe curl code sample

Copy and paste the cURL command into the box displayed on your screen.

curl code import success

If successful, you should now be able to view the cURL command in the form of an API request.

button

Secure Your APIs with API Keys

apidog api key

Apidog provides developers with the option of securing their APIs with API keys. This is a similar concept to bearer tokens, where clients will have their unique key and value pairing to ensure that they are authentic and authorized users of the API.

button

Conclusion

cURL, with its versatility and ease of use, coupled with the simplicity and stateless nature of bearer tokens, forms a powerful combination for interacting with web APIs. By incorporating bearer tokens into cURL requests, developers and users can streamline API access, ensuring secure and controlled data exchange.

However, it's crucial to remember the inherent risks associated with bearer tokens, such as interception and theft. Always prioritize secure communication protocols (HTTPS) and proper token storage practices to safeguard your data and maintain the integrity of your API interactions. By understanding the strengths and limitations of this approach, you can leverage cURL bearer tokens effectively for seamless and secure API communication.

Explore more

Apidog SEO Settings Explained: Maximize Your API Docs Visibility

Apidog SEO Settings Explained: Maximize Your API Docs Visibility

Discover how to supercharge your API documentation's visibility with Apidog's powerful SEO features. This comprehensive guide covers everything from page-level optimizations like custom URLs and meta tags to site-wide settings such as sitemaps and robots.txt.

18 June 2025

How to Protect API Specification from Unauthorized Users with Apidog

How to Protect API Specification from Unauthorized Users with Apidog

Learn how Apidog empowers you to protect API specification from unauthorized users. Explore advanced API documentation security, access controls, and sharing options for secure API development.

17 June 2025

How to Use the PostHog MCP Server?

How to Use the PostHog MCP Server?

Discover how to use the PostHog MCP server with this in-depth technical guide. Learn to install, configure, and optimize the server for seamless PostHog analytics integration using natural language. Includes practical use cases and troubleshooting.

16 June 2025

Practice API Design-first in Apidog

Discover an easier way to build and use APIs