Local Network Only?

Is it possible to use the imp wifi to communicate sensor data on the internal network only? I’m beginning a new project and don’t want to start by building a internet connected setup. I’d like to run a local instance of my software and build to a reasonably functional state before worrying about remote communication / control via public internet.

It is not - imp devices communicate directly (and only) with Electric Imp servers.

The imp can pass messages between its device and agent, and the agent can make and process HTTP requests. The reason it’s not possible to communicate on a local / internal network is because the device itself is not making and processing HTTP requests, the agent is - and the agent doesn’t live on your network, it lives “in the cloud” (i.e. on public web servers).