As of June 2018, Toxiproxy is free for for non-commercial use. It is 100 percent open source and available from GitHub. It can be used to simulate network load conditions such as VPN disconnections, slow or unreliable network conditions, or any other issues that require a special test environment.
The tool can make sure to emulate specific environments, including devices, like when testing for mobile network issues, for instance. The tool allows all responses to be specified using templates. I