IPsec-Tools is described as 'port of KAME's IPsec utilities to the Linux-2.6 IPsec implementation. It supports NetBSD and FreeBSD as well' and is a VPN Service in the Security & Privacy category. There are three alternatives to IPsec-Tools for Linux, Mac and Android. The best alternative is strongSwan, which is both free and Open Source. Other great apps like IPsec-Tools are Libreswan (Free, Open Source) and Openswan (Free, Open Source).
Openswan is an IPsec implementation for Linux. It has support for most of the extensions (RFC + IETF drafts) related to IPsec, including IKEv2, X.509 Digital Certificates, NAT Traversal, and many others.