BIM authoring for architects and engineers.

Lapin is a desktop application and a classic modeller on the IFC schema. Its interface (React, TypeScript, three.js) runs in a Tauri window and talks over a local WebSocket to Lapin's engine (C#, .NET 10, engine/), which holds the IFC model and derives its geometry with its own B-rep kernel (engine/src/Geometry) and manifold for the booleans.

Open source under the MIT licence (see LICENSE), and helpware (below). The geometry kernel was taken from BubbleBIM Pro (the author's own engine) on 25.10.2026 and is Lapin's own code since, under the same licence. manifold (Apache-2.0) and Clipper2 (BSL-1.0) are described in engine/native/README.md. The LAZ decoder is a C# port of laz-rs (Apache-2.0): its notice is in engine/src/Platform/Lapin.PointClouds/Laz/NOTICE.md.

A module has an engine half (engine/src/Modules/…: the IFC classes it authors, its commands, their geometry) and a UI half (ui/src/modules/<id>: its ribbon tabs, quick tools and property sections), or only one of them. A module's module.json lists the modules it requires.

An edition is a list of modules (products/<id>.json), completed with what they require (scripts/product.mjs). A package holds only those: a module an edition does not have is not in its engine or in its interface. A project opened in an edition without one of its modules keeps that module's elements, read-only, and saves them back untouched.

pnpm products                                   # what every edition resolves to
LAPIN_PRODUCT=lapin-architecture pnpm dev       # Core + Architecture + Drafting only
pnpm build:product lapin-architecture           # → build/lapin-architecture/bundle

Lapin is free, and it stays free. If it helps you in some way, we encourage you (we do not require it) to help someone else who needs help, in whatever way you can: your time, your skills, a hand to a neighbour, a gift to people or a cause you trust. Lapin asks nothing for itself and takes no donations.

This is a request, not a condition: the licence is MIT, and nothing here limits it.

Lapin is MIT. pnpm check:licenses (run by pnpm build and pnpm build:product) fails when a production dependency, npm or NuGet, is not under a permissive licence (MIT, ISC, BSD, Apache-2.0…), so nothing copyleft gets in by accident.

Lapin's clash detection, and parts of its realistic 3D view, follow the design, the numbers and the tests of BimGo by Aussie BIM Guru (MIT-0). Nothing is owed under its licence; we credit it anyway. What came from where is listed in docs/acknowledgements.md.

Requires .NET 10, Node 22 + pnpm, Rust (for the desktop shell).

pnpm setup        # packages, engine build
pnpm dev          # engine on ws://127.0.0.1:47810/ws, UI on http://localhost:5180
pnpm dev:desktop  # the same in the Lapin window
pnpm test         # UI (vitest) and engine (xUnit)

Note: the engine's boolean library (manifold) is built for macOS arm64 only for now.