cURL to fetch Converter

From a terminal command to fetch()

API docs, support tickets and DevTools all hand you requests as curl commands, but your front end or Node script needs fetch. Translating by hand is where bugs creep in: a forgotten header, a body that should have been JSON-stringified, or a redirect that curl did not follow but fetch does. This converter parses the command the way curl does and emits code that sends the same request.

It reads commands copied from bash or zsh (with \ line continuations and $'…' strings), from Windows cmd (^ escapes, as in Chrome’s “Copy as cURL (cmd)”) and from PowerShell (backtick continuations).

How curl options become fetch options

• -X sets method; without it the method is inferred just as curl does (POST when there is a body, HEAD for -I, PUT for -T). GET is left implicit.
• -H headers go into a headers object. A header repeated with the same name is folded into one comma-separated value.
• -d, --data-raw and --data-binary become body. When the content type is JSON and the body is a JSON object or array, the code uses JSON.stringify({...}) with a readable object literal; otherwise the exact string is sent. Several -d flags are joined with &, and curl’s implied application/x-www-form-urlencoded header is written out explicitly.
• --json sets the body plus Content-Type and Accept: application/json.
• -G moves the data into the query string; --data-urlencode and --url-query are encoded the way curl encodes them.
• -F builds a FormData; file fields (-F [email protected]) get a placeholder Blob and a TODO comment, since a web page cannot read your disk.
• -u user:pass becomes an Authorization: Basic header built with btoa; --oauth2-bearer becomes a Bearer header.
• -m/--max-time becomes signal: AbortSignal.timeout(ms).

Redirects and other differences

curl does not follow redirects unless you pass -L, while fetch follows them by default. To keep the behaviour identical, the generated code sets redirect: 'manual' without -L (with a comment explaining why) and redirect: 'follow' with it.

Some curl features have no fetch equivalent, and the converter says so instead of silently dropping them:

• -k/--insecure: fetch always verifies TLS certificates; a warning and a comment are added.
• --connect-timeout and -x proxies: noted in comments (in Node.js, an undici ProxyAgent handles proxies).
• A GET or HEAD with a body: fetch refuses to send it, so the body is left out with a warning — you probably meant -G.
• Browsers block scripts from setting Cookie and Referer; a comment notes that they only take effect in server-side runtimes.

Flags that only affect curl’s own output (-s, -v, -i) are ignored, and options such as -o or --retry produce an info note. The result is formatted with Prettier and prints the status and response text.

Credentials stay on your machine

Copied commands nearly always contain secrets: session cookies, API keys, bearer tokens. That is why the conversion runs entirely client-side. For a promise-based alternative with automatic JSON handling, see cURL to Axios; to tidy the generated code further, use the JavaScript formatter.

Examples

curl -X POST 'https://api.example.com/v1/orders?expand=items' \
  -H 'Content-Type: application/json' \
  -H 'Authorization: Bearer sk_test_4eC39HqLyjWDarjtT1zdp7dc' \
  -d '{"customer":"cus_42","items":[{"sku":"KB-104","qty":1}]}'

const response = await fetch('https://api.example.com/v1/orders?expand=items', {
  method: 'POST',
  headers: {
    'Content-Type': 'application/json',
    Authorization: 'Bearer sk_test_4eC39HqLyjWDarjtT1zdp7dc',
  },
  body: JSON.stringify({
    customer: 'cus_42',
    items: [{ sku: 'KB-104', qty: 1 }],
  }),
  redirect: 'manual', // curl follows redirects only with -L
});

console.log(response.status);
console.log(await response.text());

curl -L -u admin:s3cret --max-time 10 https://intranet.example.com/login \
  -d 'user=aisha' -d 'remember=1'

const response = await fetch('https://intranet.example.com/login', {
  method: 'POST',
  headers: {
    'Content-Type': 'application/x-www-form-urlencoded',
    Authorization: 'Basic ' + btoa('admin:s3cret'),
  },
  body: 'user=aisha&remember=1',
  redirect: 'follow',
  signal: AbortSignal.timeout(10000),
});

console.log(response.status);
console.log(await response.text());

curl ^"https://api.example.com/v1/me^" ^
  -H ^"accept: application/json^" ^
  -H ^"cookie: session=abc123; theme=dark^"

// Browsers do not let fetch set Cookie or Referer headers; they are sent as written in Node.js.
const response = await fetch('https://api.example.com/v1/me', {
  headers: {
    accept: 'application/json',
    cookie: 'session=abc123; theme=dark',
  },
  redirect: 'manual', // curl follows redirects only with -L
});

console.log(response.status);
console.log(await response.text());

Common errors and how to fix them

Related tools

• cURL to Axios
• cURL to Python requests
• cURL to Go net/http
• cURL to PHP
• JavaScript / JSX formatter
• JSON formatter
• online formatters and secret leaks