kisi – quick signal and power integrity checks for KiCad

kisi reads a KiCad layout (.kicad_pcb + .kicad_pro) and checks trace impedance, high-speed channels (loss, return loss, TDR, vias, crosstalk, skew, eye) and power delivery (regulator chain, DC IR drop, PDN impedance, temperature estimate) – in the browser, with no installation and no setup beyond the board file.

Try it in your browser with two example boards, or open your own board (it is processed locally and never uploaded).

Status. kisi is a quick project, meant to be helpful: a fast check of a board without long setup times. Results are estimates for design checks, without any warranty of correctness – not a replacement for sign-off simulation or measurement. The individual tools – impedance map with a 2D field solver, TDR and loss per net, via model, crosstalk scan, power tree, IR drop, PDN per IC, temperature estimate – are useful on their own. kisi stays a fast linear checker – IBIS, AMI and equalisers are out of scope; for sign-off, export the channel to PyBERT or a circuit simulator (why kisi is fast, and its scope).

What you get

• Impedance: every track against its target (from net class names such as 50Z, 90Z_Diff), with formulas in a second and the 2D field solver on demand; impedance along the path, loss, TDR, vias and crosstalk per net; every impedance and via result with its accuracy level (field solver, formula, estimate) and typical deviation.
• Channel: buses and device-to-device lanes through series resistors and AC-coupling capacitors, checked against interface profiles (PCIe, USB, DDR, LVDS, Ethernet, …) on loss, return loss, skew and a linear eye; differential pairs as 4-ports, multi-drop lines at every receiver, connectors with the channel behind them; a lane or a whole bus exported as SPICE subcircuits, Touchstone and a KiCad project for circuit simulators.
• Preparation: "Prepare PCB" is a checklist of what the board file lacks per category (impedance, channel, power): forms for the simple values, Apply per step, and <board>.kisi.json saved at the end; the kisi-prepare skill does the datasheet research.
• Power: the regulator chain and power flow from fields on the parts (PI_REG, PI_LOAD), DC voltage drop per rail and in the ground return, a losses map, a temperature estimate of the board and its parts, and the PDN impedance seen from every IC with recommendations.

Quick start

• Browser: the live version, or kisi.html from the latest release, offline. Drop the .kicad_pcb with the .kicad_pro (and <board>.kisi.json if there is one). KiCad 8, 9 and 10.
• KiCad: the plugin kisi-kicad-<version>.zip from the release (KiCad's Plugin and Content Manager → Install from File…) adds a button to the PCB editor that opens the board in the viewer, with its <board>.kisi.json – see Getting started.
• Command line for scripts, CI and agents (Node.js ≥ 18; every command prints JSON):

  curl -fsSLO https://github.com/riehlies/kisi/releases/latest/download/kisi.mjs
  node kisi.mjs gaps   board.kicad_pcb     # what the analyses miss
  node kisi.mjs check  board.kicad_pcb     # channel check of all interfaces
  

• Agents: Claude Code /plugin marketplace add riehlies/kisi – the skills kisi-prepare (research missing data into <board>.kisi.json) and kisi-si-pi-review; other agents can follow the same SKILL.md files.

Documentation

• Getting started – release files, the viewer's views, first commands
• Preparing a board – the gap list, <board>.kisi.json, a worked example
• Field and kisi.json reference – net class names, PI_* fields, every kisi.json key
• Models and limits – how kisi computes, accuracy, validation, estimates
• CLI reference – every command and option
• Using kisi with agents – skills and setup

All of it as one PDF: kisi-docs.pdf on every release.

Limits

• The channel check is a first look: linear transmitter and receiver from the interface profile, no IBIS models, equalisation, jitter or noise.
• 2D cross-sections and reduced via and plane models instead of a full-board 3D solution.
• Validated against HFSS cases and kisi's own 3D FDTD references; validation against other solvers and measurements is still open. Data the board file lacks defaults to estimates until <board>.kisi.json fills it in. Details: Models and limits.

Development

Build, checks and rules: AGENTS.md · structure: ARCHITECTURE.md · contributing: CONTRIBUTING.md · planned work: ROADMAP.md · field solver upstream: UPSTREAM.md.

Related tools

• js_2d_fields – Henrik Forstén's 2D field solver in the browser, used by kisi.
• KiPI – power integrity for KiCad (DC drop, PDN impedance, coupled noise).
• padne – DC voltage drop of KiCad boards with the finite element method.
• openEMS – open 3D FDTD solver, for the cases where a reduced model is not enough.

Credits

Field solver: js_2d_fields by Henrik Forstén (GPL-3.0). Example boards in kisi-examples.html: ThunderScope Rev5.3 (EEVengers, hardware under CERN-OHL-P-2.0) and LibreVNA (Jan Käberich, GPL-3.0), shrunk to what kisi reads; the licence texts are embedded with them. Fonts: Barlow, Barlow Semi Condensed and JetBrains Mono (SIL Open Font License 1.1, web/fonts/), embedded in the viewer.

About

kisi is a side project by David Riehl. It started as a visualisation tool for the course Advanced PCB Design at TU Darmstadt and grew into a general check for KiCad boards. It was also an experiment in what current AI models make possible: kisi was written with an AI coding assistant (Claude, Anthropic) – without it, a tool of this scope would not have been possible as a side project. Commits made with AI help say so in their Co-Authored-By line.

Copyright © 2026 David Riehl and kisi contributors. Licence: GPL-3.0-only (LICENSE).