What is the difference between -d and -F in curl?

-d (--data) sends a request body as application/x-www-form-urlencoded (or raw text), and implies a POST. -F (--form) sends multipart/form-data, which is what you need for file uploads, e.g. -F file=@photo.jpg. Use -d for simple key=value or JSON bodies and -F when uploading files.

How do I make curl follow redirects?

By default curl does not follow HTTP redirects. Add -L (--location) and curl will follow Location headers up to its redirect limit. Combine with --max-redirs to cap the number of hops, and -L keeps you on the final URL's response.

What does -k or --insecure do in curl?

-k (--insecure) tells curl to skip TLS certificate verification, so it connects even if the certificate is self-signed, expired or has a hostname mismatch. It is useful for local testing but dangerous in production because it removes protection against man-in-the-middle attacks.

How do I see only the response headers with curl?

Use -I (--head) to send a HEAD request and print just the response headers, or -i (--include) to print the headers followed by the body of a normal request. For verbose diagnostics including the request and TLS handshake, add -v (--verbose).

What is the curl Flags Reference?

Interactive curl command-line option reference covering HTTP methods, headers, data and form uploads, authentication, TLS, proxies, redirects and output control — each with short/long forms and an example. It runs free in your browser on Gera Tools, with nothing uploaded.

curl Flags Reference

Name: curl Flags Reference
Creator: Gera Tools
License: https://creativecommons.org/licenses/by/4.0/

Get one useful tool a week

Like this tool? Enter your email and we'll send you one genuinely useful Gera tool a week — plus a link to come back to this one. No spam, one-click unsubscribe any time.

curl is the universal command-line tool for transferring data over HTTP, HTTPS and many other protocols. Its power lives in its options: dozens of flags control the method, headers, body, authentication, TLS behaviour and output. This reference lets you search the most-used flags with their short forms and examples.

How it works

A curl invocation is curl [flags] URL. Flags either take a value (like -H 'Header: value' or -d 'body') or are simple switches (like -L or -k). Many flags have a long --name form and a single-letter short alias; this reference lists both. curl applies the flags in order to build the request, sends it, and writes the response to stdout (or to a file with -o/-O).

Common recipes

# POST JSON and follow redirects
curl -L -X POST -H 'Content-Type: application/json' \
     -d '{"name":"A"}' https://api.example.com/users

# Download a file keeping its remote name
curl -O https://example.com/archive.zip

# Basic auth, show response headers, verbose
curl -i -u user:pass -v https://example.com/private

Flag categories at a glance

Category	Key flags	What they control
Method	`-X GET/POST/PUT/DELETE/PATCH`	HTTP verb
Headers	`-H 'Name: value'`	Request headers (repeat for multiple)
Body	`-d 'data'`, `--data-binary @file`, `--json '...'`	Request body for POST/PUT
Form upload	`-F field=value`, `-F file=@path`	Multipart form data / file upload
Auth	`-u user:pass`, `--oauth2-bearer token`	HTTP basic auth, Bearer tokens
TLS	`--cacert`, `--cert`, `--key`, `-k`	Certificate pinning and verification
Redirects	`-L`, `--max-redirs N`	Follow HTTP 3xx responses
Output	`-o file`, `-O`, `-s`, `-w '%{http_code}'`	Save response, suppress noise, print status
Debugging	`-v`, `-i`, `-I`, `--trace`	Verbose request/response, headers only
Proxy	`-x proxy:port`, `--socks5 host:port`	Route through a proxy
Timeout	`--connect-timeout N`, `--max-time N`	Connection and total time limits

Notes and tips

-d implies POST and form encoding; pair it with an explicit -H 'Content-Type: application/json' (or use --json) when sending JSON. Use -F for file uploads (multipart). -s silences the progress meter for scripting, and -w '%{http_code}' prints the status code. Reserve -k/--insecure for local testing only — it disables certificate verification.

A few flag interactions worth knowing:

-d sets the method to POST implicitly. If you also supply -X GET, the body is ignored by most servers — explicitly set -X POST when using -d.
Multiple -H flags stack, so you can add several headers in one command without any joining syntax.
--retry N retries on transient failures; combine with --retry-delay and --retry-max-time for robust scripted downloads.
-o /dev/null -s -w '%{http_code}' is the canonical incantation for health-check scripts that only care about the HTTP status code.