kwasm
A standalone KLayout-powered GDS viewer with 2D and 3D views.
The product is one self-contained JavaScript file: UI, styles, icons, Three.js,
and one Rust/KLayout WebAssembly runtime. Mount it in a DOM element or an iframe;
interact through versioned JSON messages. No React implementation is included.
The protocol can export the edited in-memory design back to base64 GDS.
Use resetProject: true on loadGds when replacing it with an unrelated design;
ordinary same-project reloads retain companion configuration and camera state.
This checkout contains an unreleased breaking refactor. The examples below describe the new interface, not necessarily the currently deployed CDN/PyPI release.
Browser
Build or download the matching kwasm-VERSION.js and serve it locally or on a CDN:
<div id="viewer" style="height:600px"></div>
<script src="./kwasm-0.2.26.js"></script>
<script>
const viewer = Kwasm.mount(document.getElementById("viewer"), { viewerId: "layout" });
viewer.ready.then(() => {
window.postMessage(
{
type: "kwasm:request",
version: 2,
viewerId: "layout",
requestId: "load-1",
action: "loadGds",
gds: "YOUR_BASE64_GDS",
},
window.origin === "null" ? "*" : window.origin,
);
});
// Call viewer.destroy() when removing it.
</script>
Initial data can also be embedded with mount(element,{gds,lyp,layerstack}).
3D requires a layerstack and uses the same loaded design, active cell and layer
visibility as 2D. One viewer per page is supported.
The native runtime runs in one embedded worker so long KLayout operations do not
block the surrounding page. No extra runtime file is fetched. A restrictive CSP
must permit worker-src data: as well as WebAssembly compilation; see the public
interface for a complete policy example.
Complete public interface and examples: all mount options, messages, responses, events, origins, drawing/routing flow, Python APIs, and limits. There are no viewer URL parameters.
Python
import kwasm
kwasm.bundle("design.gds", output="design.html", layerstack="stack.json")
kwasm.show("design.gds", interactive=True, layerstack="stack.json")
The wheel ships the same JS file. Offline HTML is the default reference integration.
Pass script_url=kwasm.CDN_URL to fetch the versioned viewer at runtime after the
corresponding release is deployed, or use your own hosting URL.
kwasm bundle design.gds --lyp layers.lyp --layerstack stack.json --output design.html
kwasm view design.gds
kwasm export-layerstack your_pdk.module --output stack.json
Development
Install Rust (pinned toolchain), Emscripten 6.0.4, Node 22+, uv and just. Initialize the KLayout/Expat submodules and activate Emscripten on PATH.
git submodule update --init --recursive
npm ci
just build # one Rust binary + dist/kwasm-VERSION.js
just dev # copy identical JS into Python package
just test # Python, pure Rust and JS unit tests
npx playwright install chromium
just test-js-browser # actual built artifact, both views and embedding modes
just wheel
Developing and architecture · Feature boundaries and invariants · Refactor decisions and acceptance
License
GPL-3.0; see LICENSE. KLayout is not replaced or relicensed by this refactor. Bundled third-party components retain their own licenses, including Three.js (MIT) and Font Awesome Free. A CDN or postMessage transport does not itself determine the license obligations of a consuming application.
1 maintainer
Metadata
1 maintainer
Release files for kwasm 0.3.0
For a detailed explanation of source distributions (sdists) and built distributions (wheels), please see the package formats documentation.
Built distribution (wheel)
| File | Interpreter | ABI | Platform | Reset |
|---|---|---|---|---|
| kwasm-0.3.0-py3-none-any.whl | Python 3 | none | any | Details |
Release files / kwasm-0.3.0-py3-none-any.whl
| Download URL | kwasm-0.3.0-py3-none-any.whl |
|---|---|
| Size | 2.5 MB |
| Tags | Python 3 |
|
SHA-256 checksum How to use checksums |
8ba4b0067bc768585c9f2870f44a2d458c88f2ab3df93a785d76de558959eb3a
|
|
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| Upload date | |
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Uploaded using Trusted Publishing? What is trusted publishing? |
Yes |
| Uploaded via |
twine/7.0.0 CPython/3.13.14
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Signed by GitHub Actions, verified by PyPI on Sep 11, 2026.
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