How to properly use curl HTTP POST for sending data? or What's the correct syntax for a curl HTTP POS

Sounds like a headers issue. Some APIs are picky. For curl http post with JSON, you NEED the Content-Type header. Example:

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

If you’re still stuck, try `curl --trace-ascii debug.txt` to log everything. Also, check if the API needs HTTPS or a user-agent header.