How Do I Properly Use CURL --POST to Send Data in a Request? or What’s the Correct Syntax for CURL --

If your JSON is failing, maybe it’s the quotes? On Linux/macOS, single quotes work, but Windows hates them. Try double quotes and escape the inner ones:

`curl -X POST -H "Content-Type: application/json" -d "{\"key\":\"value\"}" http://example.com`

For form data, `-d` is standard, but some APIs want `x-www-form-urlencoded` explicitly. Check the docs!