Schematic Draft

Schematic Draft is an offline, connectivity-aware schematic editor for analog circuits, packaged as a Windows desktop application. Draw hierarchical circuits whose connectivity is an explicit fact rather than a guess about geometry, from a component library calibrated against a published reference, and take the result out as a deterministic SPICE or Spectre netlist, a publication-ready SVG/PDF/PNG, or a .vsdx you can go on editing in Visio.

It is a fork of Analog Canvas (AGPL-3.0-only) with the hosted half removed: no accounts, no cloud projects, no hosted Gallery, no Agent API, no analytics, no simulation service. The desktop shell refuses every outbound request, so "offline" is enforced rather than promised.

Download · Documentation · 中文说明 · Upstream project

Download

Windows 10 or 11, x64, from the latest release. Both files are the same program; pick whichever suits you:

• schematic-draft-<version>-win-x64.zip — extract it and the Schematic Draft\ folder inside is a complete installation. Run schematic-draft.exe in it. Nothing else to do, nothing to uninstall: the folder holds the Projects and the preferences it writes, so moving it to another drive or another machine moves your work with it.
• schematic-draft-<version>-win-x64-setup.exe — installs for the current user, so no administrator is needed. It asks which folder to install into, adds Start-menu and desktop shortcuts, and appears in Apps & features. Uninstalling keeps the Projects you saved and tells you where they are.

Either way the program writes nothing outside its own folder except the per-user registry entries that let Explorer open a .schdraft file by double-click, which the Open .schdraft files with this copy checkbox in Help → About turns off. Both copies can coexist; they do not share data. The build is not code-signed, so Windows SmartScreen may warn about an unknown publisher — More info → Run anyway.

Chinese usage notes: apps/desktop/README.md. To build it yourself, see Build it.

Highlights

• Connectivity is an electrical fact, not a drawing accident. Net membership, Junctions, Cell terminals and typed Instance terminals are recorded; geometry never silently creates a connection, and a Crossing is never quietly promoted to a Junction. An ambiguous intersection is rejected rather than guessed at. Every edit goes through one typed transaction, so multi-object changes undo as one.
• Reusable hierarchy. Author each schematic as a Cell, give it independent Cell Pins, place it as a block inside another, and navigate between callers and child Cells. The Cell interface is derived from the drawing, so a block's pins cannot drift from what is inside it.
• A component library calibrated against a reference. Built-in symbol artwork is generated from a manifest of measurements taken from a published analog-design text, which is the sole visual authority for it; parts with no such evidence live in a separate Extended Devices library and say so. Each component carries its symbol, its electrical rules and its catalog metadata in one file. Transistors holds the MOS and BJT pairs with the depletion-mode and DMOS variants, two GaN HEMTs and an IGBT beside them; Power and Ports keeps Ground, a dedicated analog and digital ground, and supply rails. Five worked circuits ship in the toolbar's Gallery panel — starter Projects inside the application, nothing fetched.
• Deterministic netlists. Export structural SPICE or Spectre — to the clipboard or straight to a file — and get the same text for the same circuit every time. Structural .cir, .sp, .spi and .scs import back in, and a block can be bound to a .subckt you brought with you. A part no standard SPICE card describes — a GaN HEMT, an IGBT — is reported as non-netlistable rather than dressed up as a MOSFET and handed silicon model parameters; bind it to a vendor .subckt and it prints as an ordinary subcircuit call.
• The drawing is yours to set for the page it goes on. Six document-wide factors — font size, wire, symbol and drawing thickness, junction dot size, and line jump size — scale between half and twice the size the drawing was tuned at, and the set is one copyable Style code that carries to the next document. Over that, any one wire or component takes its own colour and its own stroke weight, from a quarter to four times. A MOSFET can be drawn three- or four-terminal without the device changing underneath it, a wire can be told to hop over the wires it crosses, and the background grid can mark every seventh dot so a distance is read rather than counted.
• Publication-ready drawings. SVG and PDF stay vector; PNG renders at 3×. LaTeX formulas in rich-text annotations are typeset locally, with no web font and no service.
• A Visio file you can keep editing. .vsdx export writes real Visio shapes: devices carrying their reference, parameters and pins, and wires as chains of segments glued to those pins and to a draggable node at every corner. Each hop over a crossing is a link in that chain rather than geometry baked into the wire, so it can be selected, moved or deleted on its own. A .vssx stencil of the symbol library alone is there too. Whatever the package could not carry is counted in the status line as the file is written, not left for you to find later.
• Real files, plus a net underneath. Open and Save As… use the operating system's dialogs; Save and Ctrl+S overwrite the file you opened, in place, without asking. Alongside that, a bounded crash-safety copy lives in local storage — a net, never the authority.
• Offline by construction. The Electron main process blocks every network request, serves the editor from a privileged local scheme, and hands an external link to your system browser instead of loading it in-app. There is no account to make and no telemetry to turn off.

How your work is stored

The file you opened is the Project — .schdraft for a Project this application saved, or the portable .icproj.json interchange form. Save writes that file; the File menu names the exact path so overwriting is never a guess. Save As… is the only command that prompts. A new Project has no file yet, so its first Save asks once, then remembers.

Alongside that, the application keeps a crash-safety copy in its own IndexedDB, reachable through File / Recover Local Work…. It is a safety net, not a backup and not authoritative — the file on disk is.

Check and Save runs ERC and visual checks on demand and shows findings in Issues and on the canvas before saving. Findings never block a save; editing invalidates the last check without rerunning it.

Start here

• Learn the editor: Getting started, schematic hierarchy, compatibility, and troubleshooting.
• Understand the product: current architecture and documentation map.
• Develop: working rules, reading set, and test system.

Build it

Requires Node.js 24 or newer, pnpm 11.16.0 or newer, and — for the packaged .exe — a Windows machine or a Windows build step.

pnpm install --frozen-lockfile
pnpm build          # once after install, and after pulling package changes
pnpm dev            # editor in a browser at http://localhost:5173
pnpm desktop:start  # editor in the Electron window
pnpm desktop:dist   # the release zip and installer under output/desktop/

pnpm build is not optional before the first pnpm dev: the development server's Vite configuration loads some workspace packages from their built dist/ output.

pnpm desktop:dist produces the two downloads a release offers: the ready-to-run program folder as a zip, and a per-user installer that lays the same folder down with shortcuts. Either way there is no service, and nothing is written outside the program's own folder and the files you save; uninstalling keeps the Projects saved inside that folder. The zip needs zip on the PATH. Building the installer on Linux needs Wine, which is the only thing that can run the NSIS stub that writes Uninstall.exe. See apps/desktop/README.md for the shell's window, file bridge, and network-lockdown contract.

Development is plain local Git work: make a change, run the checks that cover it (pnpm test:local <paths>, then pnpm check or pnpm verify as the change warrants), and commit. There is no CI, no PR gate, and no deployment — see working rules and the test system.

What the repository contains

• apps/editor/: the React/SVG editor.
• apps/desktop/: the Electron shell — window, file dialogs, file bridge, network lockdown, and Windows packaging.
• packages/model/, packages/project-protocol/, and packages/edit-engine/: current persisted circuit model, bounded file compatibility, and the atomic mutation boundary every edit goes through.
• packages/derived/: read-only connectivity, diagnostic, and geometry projections over the persisted model.
• packages/components/: one canonical JSON file per built-in component, containing its symbol, electrical rules and catalog metadata; runtime packages consume generated projections.
• packages/spice/, packages/devices/, packages/symbols/, and packages/netlist/: structural SPICE import and dialect conversion, built-in device facts, symbol semantics, and deterministic design-netlist export.
• packages/exporters/ and packages/render-svg/: formal SVG, PNG, and PDF output.
• packages/visio/: .vsdx drawings and .vssx stencils — a sibling projection of the document, not of the flat SVG scene, because Visio needs shapes, pins and glue a picture no longer carries.
• packages/math-typesetting/: bounded LaTeX formula typesetting for rich-text annotations.
• netlists/: one circuit per directory, the SPICE import and export corpus.
• fixtures/: Project, SPICE, export, and visual-reference test inputs and goldens.
• scripts/: symbol and component generators, golden checks, the production smoke check, the desktop close-guard window check, the Windows sync helper, and the Visio open check.
• docs/: current architecture, user guides, normative contracts, ADRs, and remaining work.

The Razavi reference manifest is the sole visual authority for component artwork.

Netlist conversion

convertNetlist in packages/spice translates structural SPICE and Spectre netlists in-process; SCS import uses it. No daemon, simulator or account is involved. The structural subset adapts netlist-crawler under its MIT license. See the conversion contract for supported syntax and the attribution.

License

Upstream Analog Canvas: copyright © 2026 Zengchun Chen and Zhishuai Zhang.

Except where otherwise noted, this software is licensed under the GNU Affero General Public License v3.0 only (AGPL-3.0-only), inherited from upstream. Modified versions that are distributed or made available for remote network interaction must provide their Corresponding Source under the same license. Third-party dependencies, reference material, and assets retain their respective copyright and license terms.

Upstream work this fork is derived from:

Zengchun Chen and Zhishuai Zhang. Analog Canvas. 2026. Source code: https://github.com/cascode-ai/analog-canvas