How to properly send a curl post request with JSON data? or Why is my curl post request returning a 4

400 usually means malformed request. For curl post requests, double-check:
- JSON is *exactly* right (no trailing commas, quotes match).
- URL is correct (no typos).
- Headers are included (`Content-Type` is a must).

Use `curl -v` to see what’s actually being sent. If it’s still unclear, paste the verbose output here—we’ll help!