The best alternatives to Visual ProtoStack are Zen Flowchart, Simply5 CloudLAN, and Arclight. If these 3 options don't work for you, we've listed a few more alternatives below.
CloudLAN is an easy to adopt, Managed VPN solution which helps businesses to secure & set up employee remote access to resources like servers, databases, applications & services. Increase your business productivity without compromising your data security.
An open source server virtualization management solution based on QEMU/KVM. Manage virtual machines, containers, highly available clusters, storage and networks with an integrated, easy-to-use web interface or via CLI.