Why Kessetsu?

Kessetsu connects jobs that are often separate: describe a circuit, validate connections, simulate, check engineering requirements, draw a schematic and export editable artifacts. It uses Ngspice for simulation, not a replacement physics engine.

What it adds to a SPICE workflow

• A compact circuit language with units, named parameters and reusable modules.
• Structural ERC and diagnostics before simulation.
• Executable assertions with actual measurements and explicit failure reasons.
• Automatic schematics and seven visual, numeric and editable engineering exports.
• The same circuit semantics in a no-install browser workspace and a local CLI.

You can use Ngspice directly when its broader netlist language is what you need. Kessetsu is useful when you want the complete edit → verify → draw → handoff loop in one workflow. It does not promise every SPICE construct, better electrical results or faster execution.

Use your own AI agent

An agent writes .kess, invokes kess check or kess test --format json, reads the diagnostics and measured failures, then revises the design. No Kessetsu AI subscription is needed. Keep acceptance limits in a separate .kessreq when the agent must not change them. See the agent cookbook.

Keep working in your preferred EDA tool

KiCad and LTspice remain full graphical design environments. Kessetsu produces editable schematics so you can continue there; source-level assertions and model dependencies do not automatically become native EDA features. Review the export reference.

Know what a result means

A passing assertion establishes a result for the supplied model and simulation conditions, not a physical hardware guarantee. Generic models can omit important device effects. The component reference and model catalog explain those boundaries.

Start with the tutorial, Web editor or CLI installation.