Pf is included in FreeBSD and macOS, and by extension pfsense. But it's worth noting that they've all diverged to varying degrees so you've gotta be careful in terms of syntax and features.

For fun I've been monkeying around with a friendly pf library in everyone's favorite language, and the differences between bit me a few times… although it looks like FreeBSD-current is starting to work towards convergence. It's a really powerful tool, but it's also been a reminder about how much I dislike C APIs.