IPHM (IP Header Manipulation) is the ability to send packets with a forged source address and have them actually leave the network. It requires raw sockets and a provider that isn't filtering forged source IPs on egress — something BCP38 (RFC 2827) told ISPs to enforce a quarter century ago, and large parts of the internet still don't.
SpooferAPI tells you, in one shot, whether your host can spoof. Nothing is logged, nothing is published — the service runs entirely in memory and your result is discarded a few minutes later.
Run the following command to check if you can spoof:
$ curl -fsSL https://iphm.net/test | sudo sh