Fetch to cURL Converter
Convert literal JavaScript fetch() requests into POSIX-shell cURL commands without executing the source.
Supported input uses a literal HTTP(S) URL and a literal RequestInit object. Dynamic variables, computed headers, Request objects, FormData, streams, and executable expressions stop with an error instead of being guessed.
cURL Output
cURL Command
Generated cURL command will appear here.
Where a fetch() request maps cleanly to cURL
An HTTP method, absolute URL, literal headers, and a literal body have direct command-line equivalents. The parser deliberately stays inside that boundary. A URL stored in a variable, a computed header object, FormData, a stream, or an arbitrary expression may depend on runtime state, so converting it without executing code would be guesswork.
String bodies are preserved as text. JSON.stringify(...) is accepted only when its argument is a JSON-compatible literal object or array. When a string body has no explicit Content-Type, the converter preserves Fetch's automatic text/plain;charset=UTF-8 instead of allowing curl's data default to change it. GET and HEAD bodies are rejected because Fetch does not allow them.
Browser behavior that a terminal command cannot copy
Fetch carries browser rules around CORS, credentials, cache mode, referrer policy, integrity checks, abort signals, and other RequestInit fields. cURL is not running inside the browser security model, so those settings are surfaced as notes rather than turned into misleading flags. Redirects are the main exception: Fetch follows redirects by default, so supported follow-mode requests include --location --max-redirs 20.
Shell quoting is part of request safety
The generated command targets a POSIX-style shell. Single quotes are the default because they prevent normal shell expansion; embedded single quotes are escaped using the standard close-escape-reopen pattern. Double-quote mode also escapes backslashes, double quotes, dollar signs, and backticks before the value is placed on the command line.
Masking covers credential-like headers and query keys such as tokens, API keys, passwords, and session identifiers. It does not rewrite the request body, because changing arbitrary body data could silently change the request itself. Replace private body fields before sharing a command.
References for the behavior above
Fetch request semantics come from the WHATWG Fetch Standard. The official cURL man page documents --request, --data-raw, --location, and --compressed. MDN's Request constructor reference is useful when checking relative URLs and browser-side RequestInit behavior.