cURL to Fetch

About this tool

Every browser DevTools panel has a 'Copy as cURL' option, but your codebase is JavaScript and what you need is a fetch() call. This tool converts simple cURL commands into a fetch() snippet as you type. It reads the URL that directly follows curl, the method from -X, every -H header written in quotes, and a body passed with --data or --data-raw. The output always sets method (GET when -X is absent, even when a body is present) and passes the body as a plain string. The parser is basic: it does not understand -d, -u, -F, --json or --data-urlencode; a body that contains quote characters, such as JSON wrapped in single quotes, is cut off at the first quote; and if a flag comes before the URL, the flag is taken as the URL. Check the output against the original command before using it. The conversion runs entirely in your browser, so Bearer tokens and session cookies in the cURL string never touch a server.

Why use it

• Headers Translated: Every quoted -H flag becomes a key-value entry in the fetch headers object, keeping header names and values as written, including Authorization, Content-Type and custom API keys.

• Method Mapping: The -X value (POST, PUT, PATCH, DELETE and others) becomes the upper-cased method property.

• Form and Text Bodies: A --data or --data-raw value without quote characters, such as name=Alice&role=admin, becomes the body string unchanged.

• Live Output: The fetch() snippet regenerates on every keystroke, so you can adjust the cURL command and watch the result change.

• Local Conversion: The entire conversion happens inside your browser using JavaScript string parsing. Bearer tokens, session cookies, and API keys embedded in the cURL command are never transmitted to any server.

How to use

1. Write or paste a cURL command with the URL directly after curl, for example curl https://api.example.com/users -X POST.
2. Put -H headers in quotes and pass any body with --data or --data-raw.
3. Watch the equivalent fetch() call appear in the fetch() output box as you type.
4. Check the method, headers object and body against the original command, especially for JSON bodies and DevTools copies.
5. Select and copy the snippet from the output box and paste it into your async function or file.
6. Add .then() / await response.json() and error handling before shipping

When it helps

• You have a short cURL example with a URL, -X, -H and a simple --data body and want it as fetch code
• You are migrating a shell script that uses simple cURL calls to a Node.js service
• You received a cURL example from an API vendor's documentation and want a starting point for a fetch call
• You want a headers object generated from a list of -H flags without retyping each one
• You are learning how cURL options map to fetch() options

Examples

curl https://api.example.com/me -H "Authorization: Bearer abc123"

fetch("https://api.example.com/me", {
  method: "GET",
  headers: {
    "Authorization": "Bearer abc123"
  }
});

curl https://api.example.com/users -X POST -H "Content-Type: application/x-www-form-urlencoded" --data "name=Alice&role=admin"

fetch("https://api.example.com/users", {
  method: "POST",
  headers: {
    "Content-Type": "application/x-www-form-urlencoded"
  },
  body: "name=Alice&role=admin"
});

curl https://api.example.com/users/42 -X DELETE

fetch("https://api.example.com/users/42", {
  method: "DELETE"
});

Tips

• After conversion, add credentials: 'include' if the original cURL used session cookies that need to travel with the browser request.
• DevTools-copied cURL commands often include browser-specific headers like sec-ch-ua and sec-fetch-site — trim those before using in a non-browser context.
• Use AbortController with a setTimeout to mirror cURL's --max-time flag and prevent hung requests in production code.
• For Node.js 18+ you can use the built-in fetch directly; for older versions, replace it with the undici or node-fetch package.
• For JSON bodies, set body: JSON.stringify({...}) in the output yourself; the converter does not parse JSON and stops at the first quote inside the data.

Frequently Asked Questions

Glossary

cURL

A command-line tool for transferring data with URLs. It supports dozens of protocols and is the de facto standard for testing HTTP APIs from a terminal.

fetch

A browser and Node.js built-in API for making HTTP requests. It returns a Promise and is the modern replacement for XMLHttpRequest in web applications.

HTTP method

The verb that describes the intended action of an HTTP request: GET retrieves data, POST submits data, PUT replaces a resource, PATCH updates it partially, and DELETE removes it.

Header

A key-value pair sent with an HTTP request or response to convey metadata such as content type, authorization credentials, caching directives, or custom application context.

Request body

The optional data payload sent with POST, PUT, or PATCH requests. Common formats include JSON (application/json) and form-encoded data (application/x-www-form-urlencoded).

CORS

Cross-Origin Resource Sharing is a browser security mechanism that restricts web pages from making requests to a different origin unless the server explicitly allows it via Access-Control-Allow-Origin headers.