Does this send my curl command anywhere?

No. Parsing and code generation both run in your browser with JavaScript. The curl command never leaves your device.

What curl flags are supported?

Common flags: -X/--request, -H/--header, -d/--data/--data-raw/--data-binary, -F/--form, -u/--user, -b/--cookie, -G/--get, -A/--user-agent, and --url. Unrecognized flags are ignored.

How does it handle -u for basic auth?

It emits an Authorization header built with btoa() at runtime, so credentials are encoded correctly when the generated code executes rather than baked in as a literal string.

What happens with -F form fields?

They are converted into a FormData object with one append() call per field. The Content-Type header is left out so the browser sets the correct multipart boundary automatically.

Why does my Cookie or User-Agent header not work when I run the code?

Browsers block scripts from setting certain headers (Cookie, User-Agent, Host) on fetch requests for security reasons. The generated code still shows them so you can see what curl sent; move that logic server-side if you need it enforced.

Can it detect a JSON body automatically?

Yes. If the request body parses as valid JSON, the tool formats it as a JavaScript object passed through JSON.stringify() instead of a raw string.

cURL to JavaScript

Name: cURL to JavaScript
Availability: InStock
Author: Nham Vu

Paste a curl command and get equivalent JavaScript fetch() code with headers, method, and body preserved.

Paste curl Command

Use async/await

JavaScript fetch() Code

// Paste a curl command on the left to see fetch() code here.

Copied!

Summary

Paste a curl command and get equivalent JavaScript fetch() code with headers, method, and body preserved.

How it works

Paste a curl command into the left panel, or click "Load Example" to try one.
The tool parses the command as you type and shows equivalent fetch() code on the right.
Toggle "async/await" to switch between an async function and a .then() chain.
Click "Copy Code" to copy the generated JavaScript to your clipboard.
Paste the result into your script and adjust variable names as needed.

Use cases

Turn a curl command copied from browser DevTools into fetch() code for a frontend script.
Migrate API examples from documentation that only ships curl snippets.
Convert a curl command from a bug report into runnable JavaScript for debugging.
Prototype a fetch() call quickly without hand-typing headers and body.
Understand what a long curl one-liner actually sends, broken into readable fields.
Share API call examples with frontend developers who work in JavaScript, not shell.

Frequently Asked Questions

Last updated: 2026-07-23 · Reviewed by Nham Vu