The Go Circuit Project http://gocircuit.org. The circuit reduces the human development and sustenance costs of complex massively-scaled systems nearly to the level of their single-process counterparts. It is a combination of proven ideas from the Erlang ecosystem of distributed embedded devices and Go's ecosystem of Internet application development. The circuit is an extension to the Go Language and Runtime. The circuit language is a superset of the Go language in that it includes one additional operator "spawn", designated for executing functions in newly spawned goroutines (Go's light-weight threads) on a specified remote, out-of-process runtime. In the sense that remote control is available within the source environment, the circuit can be likened to an imperative version of Erlang. Using the circuit one is able to write complex distributed applications — involving multiple types of collaborating processes — within a single circuit program (even within a single file). The circuit language used therein is syntactically identical to Go while also: Providing facilities for spawning goroutines on remote hardware, and Treating local and remote goroutines in the same manner, both syntactically and semantically. As a result, distributed application code becomes orders of magnitude shorter, as compared to using traditional alternatives. For isntance, we have been able to write large real-world cloud applications — e.g. streaming multi-stage MapReduce pipelines — in as many as 200 lines of code from the ground up. For lifecycle maintenance, the circuit provides a powerful toolkit that can introspect into, control and modify various dynamic aspects of a live circuit application. Robust networking protocols allow for complex runtime maneuvers like, for instance, surgically replacing components of running cloud applications with binaries from different versions of the source tree, without causing service interruption. The transparent source of the circuit runtime makes it easy to instrument circuit deployments with custom logic that has full visibility of cross-runtime information flow dynamics. Out of the box the circuit comes with a set of tools for debugging and profiling in-production applications with minimal impact on uptime.