GoKawiilLibreCAD in your browser
Every now and then I need to sketch a quick 2D drawing like a floor plan. I'm not a CAD user, and I don't want to install one just to draw five lines and a circle. The free options are all desktop apps: you download something, you install it, you launch it, you work locally. That's fine when you're at your own desk, but it's 2026 and it felt a little silly that I couldn't just open a tab and draw, especially without logging in.
I had never actually used LibreCAD before nor heard of it and I'm not its target user. I just wanted something for quick sketches. So instead of trying yet another desktop install, I thought: find an open-source app, and port to WebAssembly by just prompting GLM-5.2 in OpenCode to do so.
It is worth pointing out that the whole process was very hands off and "easy", but this is only thanks to huge efforts of the Qt team which seems to be investing into Wasm support quite seriously, and the entire Wasm ecosystem which seems at this point to be really quite mature.
It turned out to be at the edge of what this model can do, but with some guidance it worked out. Native vision support with some computer-use abilities would hugely help the model debug issues autonomously, GLM-5.2 lacks that capability. The result is below: the whole application (not a viewer, not a subset) compiled to WebAssembly and running right here on this site. Click and it loads (source: github.com/magik6k/LibreCAD-Web):
First load is ~18 MB compressed (Brotli). After that your browser caches it. Needs a recent Chromium-based browser (Chrome or Edge 137+) — the port relies on WebAssembly JSPI, which Firefox and Safari don't ship yet. More on why below.
Content below is entirely written by the LLM, but it does appear roughly technically accurate, just like the app appears to roughly run in browsers but probably contains horrible bugs upon closer inspection. This is purely a FAFO style no effort project, what do you expect?
What it is
LibreCAD is a free, GPL-licensed 2D CAD application. It reads and writes DXF and DWG files, supports layers, blocks, dimensions, hatching, and most of the things you'd expect from a 2D CAD tool. It's built in C++ on top of Qt and has been around since the QCad days.
This port compiles the exact same C++ source code to WebAssembly via Emscripten and Qt's official WebAssembly platform support. There is no JavaScript reimplementation, no web-native fork, no server-side rendering—the real desktop application is running in your browser tab.
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