cURL to Fetch Converter

Quick Answer

This tool converts cURL commands into JavaScript Fetch API requests you can copy into browser or frontend code.

What Is a cURL to Fetch Converter?

cURL is the command-line client API docs and DevTools use to show a request: the URL, method, headers, and body in one line. The Fetch API is the JavaScript call browsers and modern Node use for the same request. You convert when a doc shows curl and the code you are writing calls fetch().

Those commands usually come from API documentation, a teammate, or Chrome DevTools → Network → Copy as cURL. This page turns that command into code. It does not send the request.

How to Convert cURL to JavaScript Fetch

1. Copy the cURL command. Copy it from API docs or from Chrome or Edge DevTools with Copy as cURL.
2. Paste it into the converter. Put the command in the cURL field. Multiline commands with a trailing backslash are accepted.
3. Convert. Leave Auto convert on, or press Convert. Ctrl+Enter runs a conversion.
4. Review warnings. Read notes about CORS, cookies, User-Agent, TLS, and local files before you trust the snippet.
5. Copy the code. Copy or download the fetch() code. Ctrl+Shift+C copies the output.

How cURL Options Map to fetch()

The table is what this converter emits. A flag with no browser equivalent stays in the warning list.

Convert cURL JSON POST Requests

A JSON POST needs the method, Content-Type: application/json, and a body that JSON.parse accepts. The snippet uses JSON.stringify so quotes survive. Check the payload in the JSON Formatter or describe it with the JSON Schema Generator.

curl -X POST "https://api.example.com/users" \
  -H "Content-Type: application/json" \
  -H "Authorization: Bearer TOKEN" \
  -d '{"name":"John"}'

const response = await fetch("https://api.example.com/users", {
  method: "POST",
  headers: {
    "Content-Type": "application/json",
    "Authorization": "Bearer TOKEN"
  },
  body: JSON.stringify({
    name: "John"
  })
});

Convert cURL GET Requests

A GET with a query string stays on the URL. The method is omitted because fetch() already defaults to GET. Split that URL with the URL Parser or the Query String Parser if the query is the part you need to edit.

curl "https://api.example.com/users?page=2"

const response = await fetch("https://api.example.com/users?page=2");

Convert cURL Requests With Headers

Each -H is one header. Build a longer list in the HTTP Header Generator before you paste. A custom key such as YOUR_KEY is a placeholder. Create a real key with the API Key Generator and keep it on the server.

curl "https://api.example.com/users" \
  -H "Accept: application/json" \
  -H "X-API-Key: YOUR_KEY"

const response = await fetch("https://api.example.com/users", {
  headers: {
    "Accept": "application/json",
    "X-API-Key": "YOUR_KEY"
  }
});

Convert cURL With Bearer Authentication

Authorization: Bearer TOKEN is copied as a header. TOKEN is a placeholder. A production bearer token in frontend code is visible to anyone who loads the page. Inspect a token you already hold with the JWT Decoder, and keep the live secret in a server environment you can review with the .env Parser.

curl -X DELETE "https://api.example.com/users/123" \
  -H "Authorization: Bearer TOKEN"

const response = await fetch("https://api.example.com/users/123", {
  method: "DELETE",
  headers: {
    "Authorization": "Bearer TOKEN"
  }
});

Convert cURL Form Data

application/x-www-form-urlencoded is name/value pairs in the body, the same shape as an HTML form. -F is multipart. Multipart can carry a file, and the browser sets the boundary, so do not copy a cURL Content-Type that already includes a boundary. Encode a single value with the URL Encoder & Decoder if you are checking one field by hand.

curl -X POST "https://api.example.com/login" \
  -H "Content-Type: application/x-www-form-urlencoded" \
  --data-urlencode "email=test@example.com" \
  --data-urlencode "password=secret"

const response = await fetch("https://api.example.com/login", {
  method: "POST",
  headers: {
    "Content-Type": "application/x-www-form-urlencoded"
  },
  body: new URLSearchParams({
    email: "test@example.com",
    password: "secret"
  })
});

Convert Chrome DevTools “Copy as cURL” Requests

Chrome and Edge can turn a captured request into cURL. Open DevTools, choose Network, right-click the request, then Copy → Copy as cURL (bash) or Copy as cURL (cmd). Paste that text here. The converter accepts backslash continuations and Windows caret continuations, including ^& inside a quoted URL.

DevTools also copies headers the browser sets itself, such as User-Agent, Cookie, and Sec-Fetch-*. Those stay visible in the warnings. They are not silently removed, and browser fetch still will not let page JavaScript set them.

Browser Fetch Limitations

• CORS still applies. Converting the command does not make another origin accept the call.
• Host, Content-Length, Cookie, Referer, User-Agent, and Sec-* headers are controlled by the browser. Node.js Fetch can send several of them. Switch the target if that is the runtime you are writing for.
• A Cookie header from cURL does not become a working browser cookie. You may need credentials: "include" and a server that allows it.
• -k cannot turn off certificate checks in the browser.
• A pasted path such as @photo.jpg is not a file the page can read. Pick the file with an input.
• Authorization and basic auth are copied so the snippet is usable. Do not leave production credentials in frontend source. Basic auth is standard Base64, which the Base64 Encoder/Decoder can inspect. It is not encryption.

Common cURL to Fetch Conversion Mistakes

• Sending JSON with the default -d content type. Without Content-Type: application/json or --json, cURL uses application/x-www-form-urlencoded. If the single body parses as JSON, this converter switches to JSON.stringify and says that it did.
• Joining several -d flags with & and expecting one JSON object.
• Copying a multipart Content-Type, boundary included, into fetch(). The browser must set that header.
• Expecting -k, --proxy, or a client certificate to work in page JavaScript.
• Putting a session cookie or bearer token from DevTools into a public frontend bundle.
• Breaking quotes while editing the command by hand. The String Escaper shows the escaped form. Validate a JSON body with the JSON Validator before you convert again.

How This Converter Works

1. Normalize line endings and join backslash, caret, and backtick continuations.
2. Tokenize single quotes, double quotes, and escapes so a header or JSON body stays one word.
3. Parse the URL, method, repeated headers, data, forms, auth, and cookies.
4. Map those fields to fetch() or Axios options.
5. Check the result against browser limits for the target you selected.
6. Generate the snippet. GET omits the method. JSON uses JSON.stringify.
7. Attach a warning for every flag or header that fetch() cannot honor.

Shell variables such as $TOKEN are not expanded. Unknown flags are named in the warning list instead of being dropped. After the snippet looks right, sketch the response with the API Mock Generator.

Real Examples

curl "https://api.example.com/users?page=2"

const response = await fetch("https://api.example.com/users?page=2");

curl -X POST "https://api.example.com/users" \
  -H "Content-Type: application/json" \
  -H "Authorization: Bearer TOKEN" \
  -d '{"name":"John"}'

const response = await fetch("https://api.example.com/users", {
  method: "POST",
  headers: {
    "Content-Type": "application/json",
    "Authorization": "Bearer TOKEN"
  },
  body: JSON.stringify({
    name: "John"
  })
});

curl "https://api.example.com/users" \
  -H "Accept: application/json" \
  -H "X-API-Key: YOUR_KEY"

const response = await fetch("https://api.example.com/users", {
  headers: {
    "Accept": "application/json",
    "X-API-Key": "YOUR_KEY"
  }
});

curl -X DELETE "https://api.example.com/users/123" \
  -H "Authorization: Bearer TOKEN"

const response = await fetch("https://api.example.com/users/123", {
  method: "DELETE",
  headers: {
    "Authorization": "Bearer TOKEN"
  }
});

curl -X POST "https://api.example.com/login" \
  -H "Content-Type: application/x-www-form-urlencoded" \
  --data-urlencode "email=test@example.com" \
  --data-urlencode "password=secret"

const response = await fetch("https://api.example.com/login", {
  method: "POST",
  headers: {
    "Content-Type": "application/x-www-form-urlencoded"
  },
  body: new URLSearchParams({
    email: "test@example.com",
    password: "secret"
  })
});

Related Developer Tools

Assemble the URL first with the URL Builder, then paste the cURL command here. More request utilities are on the developer tools page.

• HTTP Header Generator

  Build the header list before you paste a cURL command.

• JSON Formatter

  Read the JSON body that this converter turns into JSON.stringify.

• URL Parser

  Split the request URL into host, path, and query.

• URL Builder

  Assemble the URL, including query parameters, before converting.

• API Mock Generator

  Sketch the response your new fetch() call should receive.

• JWT Decoder

  Inspect a bearer token after you remove it from frontend code.

Frequently Asked Questions