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cURL to fetch Converter

cURL to fetch Converter tool on AzWebTools.

Result

Fill inputs and click run.

How to Use This Tool

  1. Paste a valid cURL command into the input field.
  2. Select your preferred output style ('Pure fetch' with Promises or 'Async/await').
  3. Choose your preferred indentation level (e.g., 2 spaces, 4 spaces, or tabs).
  4. Click the 'Convert' button to generate the JavaScript equivalent.
  5. Copy the generated code and paste it directly into your project.

Learn More About cURL to fetch Converter

Understanding cURL and the Fetch API

cURL is a command-line tool and library used for transferring data via URLs. It supports almost every protocol and is the industry standard for demonstrating API calls in technical documentation. However, modern web applications built in JavaScript do not run cURL commands directly; they rely on browser APIs to make network requests.

The Fetch API provides a modern, global fetch() method that offers a simple, logical way to retrieve resources asynchronously across the network. It was introduced to replace the older, more cumbersome XMLHttpRequest (XHR).

Why Convert cURL to Fetch?

APIs like Stripe, Twilio, and GitHub primarily provide their documentation examples in cURL. For frontend and Node.js developers, manually translating these commands into JavaScript fetch requests can be tedious and error-prone, especially when dealing with complex headers, authentication tokens, and stringified JSON payloads. An automated converter bridges this gap, ensuring that the HTTP method, headers, and body are accurately formatted into a valid JavaScript Request object.

Key Differences Handled During Conversion

  • HTTP Methods: cURL uses -X POST or infers POST when the -d (data) flag is present. The Fetch API requires explicitly setting method: 'POST'.
  • Headers: cURL specifies headers individually using multiple -H flags. The Fetch API requires a single headers object.
  • Data Payload: cURL's -d or --data flags pass raw string data. The Fetch API requires assigning this data to the body property, often necessitating JSON.stringify() if the Content-Type is application/json.
  • Asynchronous Execution: Because network requests take time, the Fetch API utilizes Promises. Developers can handle these using traditional .then().catch() chains or modern async/await syntax.

The Origin of cURL and the Fetch API

cURL was created in 1997 by Daniel Stenberg as a command-line utility to fetch currency exchange rates. It has since grown into an industry standard for network transfers, supporting over 20 protocols. The Fetch API was introduced to web browsers around 2015 as part of the modern web platform, providing a more powerful, flexible, and Promise-based replacement for the aging XMLHttpRequest (XHR) standard.
cURL is the universal command-line tool for network requests, while the Fetch API is the modern standard for handling network operations in JavaScript.
cURL Initial Release
1997
cURL Creator
Daniel Stenberg
Fetch API Introduction
Circa 2015

Examples

Simple GET

Runtime-verified example for curl-to-fetch-converter
Input
{"curlCommand":"curl https://api.example.com/data","wrapperStyle":"Async/Await (try/catch)","indentation":"2 Spaces"}
Output
{
  "curlCommand": "curl https://api.example.com/data",
  "wrapperStyle": "Async/Await (try/catch)",
  "indentation": "2 Spaces"
}

POST with JSON

Runtime-verified example for curl-to-fetch-converter
Input
{"curlCommand":"curl -X POST https://api.example.com/submit -H \"Content-Type: application/json\" -d '{\"key\":\"value\"}'","wrapperStyle":"Pure Fetch","indentation":"2 Spaces"}
Output
{
  "curlCommand": "curl -X POST https://api.example.com/submit -H \"Content-Type: application/json\" -d '{\"key\":\"value\"}'",
  "wrapperStyle": "Pure Fetch",
  "indentation": "2 Spaces"
}

Bearer Auth

Runtime-verified example for curl-to-fetch-converter
Input
{"curlCommand":"curl -H \"Authorization: Bearer YOUR_TOKEN\" https://api.example.com/protected","wrapperStyle":"Promise (.then/.catch)","indentation":"4 Spaces"}
Output
{
  "curlCommand": "curl -H \"Authorization: Bearer YOUR_TOKEN\" https://api.example.com/protected",
  "wrapperStyle": "Promise (.then/.catch)",
  "indentation": "4 Spaces"
}

Sample Scenario

Runtime-verified example for curl-to-fetch-converter
Input
{"curlCommand":"curl -X POST https://api.example.com/users -H \"Content-Type: application/json\" -d '{\"name\":\"Alice\"}'","wrapperStyle":"Async/Await (try/catch)","indentation":"2 Spaces"}
Output
{
  "curlCommand": "curl -X POST https://api.example.com/users -H \"Content-Type: application/json\" -d '{\"name\":\"Alice\"}'",
  "wrapperStyle": "Async/Await (try/catch)",
  "indentation": "2 Spaces"
}

Use Cases

  • Translating cURL examples from API documentation into usable JavaScript code for frontend or backend applications.
  • Converting network requests copied from browser Developer Tools into reproducible fetch scripts for debugging.
  • Generating boilerplate HTTP request code rapidly for React, Vue, Angular, or Node.js environments.
  • Learning how specific cURL flags and parameters map to modern JavaScript Fetch API options.

Frequently Asked Questions

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