> ## Documentation Index > Fetch the complete documentation index at: https://docs.hyperwisor.com/llms.txt > Use this file to discover all available pages before exploring further. # Circuit Builder > Design and simulate hardware circuits for your product. The **Circuit Builder** (Develop → Circuit Builder) is where you design and simulate the hardware circuit for your product — lay out components and connections and validate the wiring before you build physical hardware. ## What it's for * Plan the circuit your product's firmware will run on * Simulate connections to catch issues early * Document the hardware design alongside the rest of the product Pair it with the [Firmware SDK](/firmware/overview) (the code) and a [hardware module](/hardware/overview) (the physical board) to go from design to a working device. Define your product's command vocabulary.