Convert curl Commands to JavaScript: fetch vs axios
Turn curl commands into JavaScript fetch or axios code in one click. Parse headers, body, and auth—with examples, fetch vs axios comparison, and best practices.
🔄 From curl to Code: One Paste, Multiple Languages
API docs and support threads often give you a curl command. Your app runs in JavaScript or TypeScript. Manually rewriting curl into fetch or axios is tedious and error-prone. This guide shows you how to convert curl to fetch or axios in seconds, when to use each, and how to avoid common mistakes—using our free curl to Code Converter.
Why Convert curl to JavaScript?
curl is the universal way to show “how to call this API.” Your frontend or Node app needs real code. Converting curl to JavaScript helps when:
📖Docs & Testing
- •API documentation usually provides curl examples—turn them into runnable JS
- •Copy curl from browser DevTools (Network tab) and get equivalent fetch/axios
- •Test endpoints quickly in a script or REPL without leaving your editor
🛠️Integrate Into Your App
- •Drop the generated code into React, Next.js, Node, or any JS project
- •Preserve headers, body, method, and auth—no manual translation
- •Switch between fetch and axios (or other languages) with one click
Using the curl Converter Tool
Our curl to Code Converter parses a curl command and outputs ready-to-use code. Step by step:
1Paste the curl Command
Copy the full curl command from docs, DevTools, or Postman (export as curl). Paste into the input field. The tool parses -X, -H, -d, -u, and URL.
💡 Tip: Multi-line curl (with backslashes) is supported. If parsing fails, check for missing quotes around headers or body.
2Choose Output: fetch or axios
Select JavaScript (fetch) or axios. Some tools also offer Node (native https), Python, or other languages. Pick the one that matches your stack.
3Copy and Use
Copy the generated snippet into your project. Add error handling, async/await, or response checks as needed. The converter gives you the request structure; you own the control flow.
fetch vs axios: Which to Choose?
Both can do the same HTTP calls. The difference is API style and features:
fetch (native)
Pros
- • No dependency; built into browsers and Node 18+
- • Promise-based; works with async/await
- • Smallest bundle impact
Cons
- • Manual
response.json(); no throw on 4xx/5xx by default - • No interceptors; no built-in timeout (use AbortController)
axios
Pros
- • Auto JSON parse; throws on bad status codes
- • Interceptors for auth, logging, retries
- • Timeout, cancel with CancelToken/AbortController
Cons
- • Extra dependency and bundle size
- • One more package to maintain
Use fetch when you want zero dependencies and simple requests. Use axios when you need interceptors, consistent error handling, or a nicer API across many API calls.
Example: curl → fetch and axios
A typical POST with JSON body and Bearer token:
curl
curl -X POST https://api.example.com/users \
-H "Content-Type: application/json" \
-H "Authorization: Bearer token123" \
-d '{"name": "John", "email": "john@example.com"}'fetch
const res = await fetch('https://api.example.com/users', {
method: 'POST',
headers: {
'Content-Type': 'application/json',
'Authorization': 'Bearer token123'
},
body: JSON.stringify({ name: 'John', email: 'john@example.com' })
});
if (!res.ok) throw new Error(`HTTP ${res.status}`);
const data = await res.json();axios
const { data } = await axios.post(
'https://api.example.com/users',
{ name: 'John', email: 'john@example.com' },
{ headers: { Authorization: 'Bearer token123' } }
);Best Practices
After converting, apply these practices so your code is robust:
✓Check Response Status
With fetch, response.ok is only true for 2xx. Always check res.ok or res.status before parsing JSON, and throw or handle 4xx/5xx. With axios, non-2xx responses throw—catch and handle them.
⏱️Timeouts & Cancellation
Use AbortController with fetch (pass signal) or axios timeout/cancel to avoid hanging requests. Especially important in UI or serverless.
🔐Don’t Hardcode Secrets
The converter will include whatever is in the curl (e.g. Bearer token). Replace with env vars or a secure config (process.env.API_KEY, etc.) before committing.
Common Pitfalls
Avoid these mistakes when using converted code:
❌Forgetting JSON.stringify for Body
With fetch, the body must be a string. For JSON you need body: JSON.stringify(obj). Passing an object directly will cause a silent failure or wrong request.
⚠️Assuming 2xx When Using fetch
fetch does not throw on 404 or 500. You must check res.ok or res.status and then parse. Otherwise you may try to res.json() on an error body and get confusing errors.
🌐CORS in the Browser
curl has no CORS. In the browser, the same URL might fail with CORS errors if the server doesn’t allow your origin. Use a proxy, backend-for-frontend, or ensure the API sends the right CORS headers.
Pro Tips
Get more from the converter and your HTTP code:
📋Copy curl From DevTools
In Chrome/Firefox DevTools, open Network, click a request, and use “Copy as cURL” (or “Copy as fetch”). Paste into the converter to get axios or another target language with the same headers and body.
🔗Combine With JWT and JSON Tools
If the request uses a Bearer token, decode it in the JWT Decoder to check expiry or claims. Paste JSON request/response bodies into the JSON Formatter to validate and pretty-print.
✅ Convert curl to fetch or axios in One Click
Use our curl to Code Converter to turn any curl command into JavaScript (fetch), axios, or other languages. Paste from docs or DevTools, pick your format, and copy. Free, no sign-up, and runs in your browser.
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