How are query parameters handled in cURL -G commands?

When cURL uses -G or --get with data flags, the parameters are automatically appended to the target URL query string in the generated fetch code.

Does this converter execute my cURL command?

No. The conversion is a purely textual grammar transformation that parses arguments without executing commands or connecting to remote servers.

Why does my converted fetch() request fail with a CORS error in the browser while cURL succeeds in the terminal?

cURL is an operating system CLI tool that bypasses browser Same-Origin Policy (SOP). Web browsers enforce Cross-Origin Resource Sharing (CORS) rules on fetch() requests to protect users. If the target server does not send "Access-Control-Allow-Origin" headers allowing your domain, the browser will block the response even though cURL worked fine.

How does the converter handle Bearer token and custom API key headers?

The converter parses "-H", "--header", or "-u" flags and maps them directly to the fetch options "headers" object. Tokens passed via "-H "Authorization: Bearer "" are faithfully preserved in the converted fetch configuration without storing or logging your credentials.

What is the difference between cURL -d and --data-raw when converting to fetch?

In cURL, "-d" or "--data" sends POST data and strips newlines from files, whereas "--data-raw" passes the string literally without interpreting "@" file syntax. The converter serializes both into the fetch "body" option, automatically wrapping JSON objects with JSON.stringify() and setting "Content-Type: application/json".

Does fetch() reject its Promise on HTTP 404 or 500 status codes?

No. Unlike libraries like Axios, browser fetch() only rejects its Promise on network failure or DNS errors. For HTTP 400, 404, or 500 error responses, fetch() resolves normally with response.ok set to false. The generated code includes response.ok checks to handle non-2xx responses gracefully.

developer-tools100% Client-Side LocalDeveloper

cURL to Fetch Converter

Convert common cURL commands into JavaScript fetch() requests directly in your browser.

Privacy Guarantee: Runs 100% locally in your browser. Your cURL commands, API headers, and request bodies are parsed client-side without sending data to any external server.

Local Syntax Transformation: cURL commands are converted strictly in your browser. Sensitive API tokens, basic auth credentials, and request payloads never leave your computer.

cURL Command Input

Presets:

233 characters

JavaScript fetch() Output

Include TypeScript Interface

async function executeRequest() {
  try {
    const response = await fetch("https://api.example.com/v1/auth/login", {
  method: "POST",
  headers: {
    "Content-Type": "application/json",
    "Accept": "application/json",
    "User-Agent": "MyApp/2.0",
  },
  body: JSON.stringify({
  "email": "developer@example.com",
  "password": "secure_password_123"
}),
});

    if (!response.ok) {
      throw new Error(`HTTP error! status: ${response.status}`);
    }

    const data = await response.json();
    console.log("Success:", data);
    return data;
  } catch (error) {
    console.error("Fetch Error:", error);
    throw error;
  }
}

// Call the function
executeRequest();

Command AnalysisPOST

URL:https://api.example.com/v1/auth/login

Headers:3 headers parsed

Payload:{"email":"developer@example.com","password":"secure_password_123"}

How to Use

Paste any valid cURL command (e.g. from Chrome DevTools, Postman, or terminal history) into the input box.

Select your preferred output style: modern async/await function or traditional Promise .then() chaining.

Enable the TypeScript interface toggle to automatically infer request payload types and typed response boilerplate.

Review generated headers, credentials mode (include/same-origin), and JSON.stringify body payload formatting.

Copy the ready-to-run JavaScript/TypeScript snippet to your clipboard or integrate it directly into your frontend code.

Why Use cURL to Fetch Converter?

Zero Server Transmission

Transforms shell commands purely within client memory without making external network calls.

Async/Await & Promise Styles

Generates modern async/await boilerplate or standard Promise chaining.

Automatic Basic Auth Conversion

Converts -u / --user flags into proper Authorization: Basic base64 headers.

TypeScript Interface Generation

Optionally includes typed return signatures for TypeScript codebases.

About This Tool

The cURL to Fetch Converter translates command-line cURL commands into clean, readable JavaScript and TypeScript fetch() code. It extracts HTTP methods, custom headers, basic authentication, query parameters, and JSON payloads while warning about flags that cannot be represented in browser environments.

Tags:#curl to fetch#curl to fetch converter#convert curl to fetch#curl to javascript#curl to js fetch#cURL command converter

Frequently Asked Questions

Not all. Browser security policies prevent client scripts from modifying certain headers (like User-Agent or Cookie directly) or bypassing TLS certificate checks (-k/--insecure). The converter flags these differences with clear warnings.

Companion Guides & Technical Insights

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