cURL to JavaScript Fetch API Converter
Transform cURL commands into modern JavaScript and Node.js 20+ Fetch API calls with typed headers and JSON.stringify payloads.
How do I use cURL to JavaScript Fetch API Converter?
Paste your cURL command into the left input editor (or inspect the pre-loaded GraphQL POST cURL sample).
Verify that 'JavaScript (Fetch)' is active in the target language bar.
Review the generated `fetch(url, { method, headers, body })` code with automatic `JSON.stringify()` formatting.
Click 'Copy' to use the snippet in Next.js Server Actions, React hooks, Cloudflare Workers, or Node.js.
What features does cURL to JavaScript Fetch API Converter offer?
Pre-configured for zero-dependency Web Standard `fetch()` (Browser, Node.js 20+, Bun, Deno, Edge Workers)
Automatically parses JSON `-d` bodies into clean `JSON.stringify({...})` expressions
Extracts all `-H` flags into a structured `headers` object literal
Pre-loaded with a GraphQL API query + variables cURL example for immediate testing
Instant 1-click switch to Axios, Python Requests, or Go `net/http` if your stack changes
100% Client-Side privacy: Bearer tokens and GraphQL variables stay in your browser memory
cURL CLI Flags to Web Standard `RequestInit` Fetch Options
The WHATWG `fetch(input, init)` API accepts a `RequestInit` configuration object that maps directly to cURL flags.
| cURL Argument | Fetch `RequestInit` Property | Data Type | Runtime Behavior |
|---|---|---|---|
| -X PATCH / POST | method: 'PATCH' | 'POST' | string | Defaults to 'GET' if omitted |
| -H 'Authorization: ...' | headers: { Authorization: '...' } | Record<string, string> | Sent on preflight CORS if non-simple |
| -d '{"query":"..."}' | body: JSON.stringify({...}) | string | FormData | Must be serialized string, not raw object |
| -b / --cookie | credentials: 'include' | RequestCredentials | Browser forbids manual Cookie header in CORS |
How is cURL to JavaScript Fetch API Converter used in real-world workflows?
Converting Third-Party API Docs into Server Actions & Route Handlers
Turn Stripe, Resend, or GraphQL cURL examples from documentation directly into native `fetch()` calls for Next.js App Router without installing extra HTTP packages.
Writing Zero-Dependency Edge Fetch Requests
Edge runtimes rely on the WinterCG standard `fetch()` API—convert complex webhook and REST cURL commands into lightweight V8 isolate code.
Reproducing API Requests in the Browser DevTools Console
Convert a backend engineer's cURL command into a `fetch()` snippet you can paste and run directly inside the Chrome DevTools Console.
Frequently Asked Questions about cURL to JavaScript Fetch API Converter
Why does `fetch()` not reject the Promise on HTTP 404 or 500 errors?
Unlike Axios, the Web Standard `fetch()` API only rejects its Promise on network failures (such as DNS lookup failure or CORS block). For HTTP 4xx/5xx responses, `fetch()` resolves normally with `response.ok === false`, so always check `if (!response.ok) throw new Error(response.statusText)`.
Why must I wrap the JSON object in `JSON.stringify()` in Fetch?
Passing a plain JavaScript object to `body: { ... }` causes the browser to coerce it via `.toString()` into the literal string `"[object Object]"`. Our converter automatically wraps JSON payloads in `JSON.stringify(...)`.
Why does the browser ignore the `Cookie` header in `fetch()`?
In browser environments, `Cookie` is a forbidden header name under the Fetch specification for security reasons. To send cookies cross-origin from a browser, add `credentials: 'include'` to your `fetch()` options instead.
Does this converter work for Node.js 20 and 22 native fetch?
Yes! Node.js 18+ includes global `fetch` (powered by Undici) out of the box, so the generated JavaScript snippet runs in both browsers and modern Node.js without any `node-fetch` dependency.
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