Pascal Editor is an open source 3D architectural editor that runs in your browser, renders with WebGPU, and lets AI agents edit real building models through the Model Context Protocol (MCP). It is free, MIT-licensed, and local-first, so your projects stay on your machine unless you choose to share them. If you have ever wished CAD software felt as light as a web app and as programmable as an API, this is the project to watch.
Key Takeaways
Pascal Editor is a browser-based 3D building editor: draw walls, rooms, levels, roofs, and furniture without installing heavy desktop CAD software.
It renders with WebGPU through React Three Fiber, and it is local-first: projects live in SQLite on your own machine.
AI agents connect over MCP, locally or hosted, and can create, inspect, edit, and validate scenes, while humans keep full undo and manual control.
It is MIT-licensed and published on npm as `@pascal-app` packages, so you can embed the viewer or the full editor in your own product.
Run it in seconds with `npx @pascal-app/cli editor`, or self-host it with one Docker container.
What Pascal Editor actually is
Pascal Editor describes itself as an "open-source 3D architectural editor with a local CLI, MCP tools, and practical workflows for humans and AI agents." The repository, pascalorg/editor, holds 25,226 stars and 3,139 forks on GitHub, and it is licensed under MIT. It was created in October 2025 and has grown to more than 2,100 commits across 32 releases.
The editor models a building as a semantic scene graph: Site, Building, Level, then walls, slabs, ceilings, roofs, zones, doors, windows, and furniture. Every element stays editable, which is the detail that makes the whole project work. A model an agent builds is one a person can open, correct, and keep working on, and a model a person draws is one an agent can read and change. That two-way readability is rare in CAD, where files are usually either human-friendly or machine-friendly, but not both.
A live demo at editor.pascal.app shows where the project is heading: a reconstructed home you can inspect with exploded views, section cuts, X-ray views of building systems, and first-person walkthroughs. The project is upfront that this "Pascal Next" preview is not yet part of the open source editor release, so treat it as a direction, not a promise.
Why WebGPU in the browser matters
Traditional CAD tools are heavyweight desktop installs with steep learning curves and proprietary file formats. Pascal Editor bets on the opposite: the browser is the platform, and WebGPU is the renderer. Its stack is modern web tooling all the way down: React 19 and Next.js 16, Three.js with a WebGPU renderer, React Three Fiber, Zustand for state, Zod for schemas, Zundo for undo and redo, and three-bvh-csg for boolean geometry like door and window cutouts.
That choice has practical consequences. Scenes persist to IndexedDB in the browser with a 50-step undo history, so a misclick is recoverable. Geometry systems regenerate only the nodes that changed each frame, which keeps editing responsive even as a model grows. And because the viewer and editor ship as npm packages, a team can drop a live, interactive 3D scene into its own product with an iframe or a React component, instead of building a renderer from scratch.
The trade-off is honest too: WebGPU needs a modern browser with WebGPU support. Older environments fall back instead of rendering the live editor, so this is a tool for current hardware, not every device ever made.
The part that makes it different: AI agents that can actually edit
Plenty of tools claim AI features. Pascal Editor gives agents a real interface. Its MCP server exposes scene tools, resources, and prompts to MCP-compatible hosts, and the project ships two public agent skills, `pascal-3d` for safe scene work and `furniture-fit` for evidence-based footprint assessments, installable with `npx skills add pascalorg/editor`. Claude Code and Codex users can install the same skills as a plugin from the repository marketplace.
There are two ways to connect an agent. Locally, the Pascal CLI starts an authenticated MCP service in the background and `pascal mcp connect` needs neither the editor process nor an account. Hosted, the MCP server at `https://editor.pascal.app/api/mcp` speaks Streamable HTTP and works with Claude, Codex, Cursor, and VS Code with GitHub Copilot. The hosted server is also listed on Smithery under the manifest name `app.pascal/editor`.
The design keeps humans in charge. Agent edits land in the same project you open in the editor, and you can review, undo, and keep editing them by hand. One active agent client per local CLI service is the stated rule, which avoids two agents fighting over the same scene state.
How to run it yourself
You have three honest options, depending on how much control you want:
Option | Command or image | Best for |
|---|---|---|
Local CLI | `npx @pascal-app/cli editor` | Trying it fast, keeping projects on your machine |
Self-hosted | `ghcr.io/pascalorg/pascal-editor` | Teams that want their own instance behind one admin password |
Embed | `npm install @pascal-app/core @pascal-app/viewer @pascal-app/editor` | Products that need a viewer or editor inside their own app |
The CLI needs Node.js 22.23.4 or newer on the 22.x line, 24.22.1 or newer on 24.x, or 26.12.1 or newer, and it keeps projects in `~/.pascal/data/pascal.db`. The Docker image stores projects in SQLite under `/data`, reads `PASCAL_PUBLIC_URL` at runtime, and serves any domain from the same image. The project also supports a plugin model: new node kinds and sidebar panels ship as plugins through the same manifest the built-ins use, and pascalorg/plugin-trees is a worked example with procedural trees, flowers, and grass.
Export is practical, not locked in: a scene downloads as GLB, USDZ, STL, OBJ, or IFC4, as 3D-print-ready parts, or as a PDF floor plan. Building, editing, and sharing projects is free, and the editor itself is open source; paid credits on the hosted service cover AI work such as assistant messages, Studio renders, and generated items, per the project's own FAQ.
Who should try it, and who should skip it
Try Pascal Editor if you are an architect or interior designer curious about browser-based layout work, a developer who wants an embeddable 3D viewer, or an AI engineer who wants an agent to manipulate spatial models through a real protocol instead of screenshots. The local-first design also suits anyone who wants to keep building data off third-party servers.
Skip it for now if you need full BIM certification workflows, structural engineering analysis, or a mature plugin marketplace. This is a fast-moving project from late 2025, not a decades-old CAD suite, and its hosted "Pascal Next" preview is explicitly not the shipped editor yet. Evaluate it for layout, room planning, roof studies, and interior scenes, which is where it is strongest today.
FAQ
Is Pascal Editor really free?
Yes. The viewer, editor, scene engine, and MCP server are MIT-licensed on GitHub, and building, editing, and sharing projects costs nothing. Paid plans on the hosted service cover AI credits and hosted API access, not the open source editor itself.
Do I need an account to run it locally?
No. The local CLI needs no Pascal account or API key, and local projects stay on your machine unless you choose to share them. The hosted MCP server is the part that uses sign-in or an API key.
Can an AI agent break my model?
Agents edit the same scene you do, but every change is undoable, scenes persist with history, and you can keep editing by hand afterward. Start agents on a copy of a project if you want a safety net.
How is this different from Blender or FreeCAD?
Blender and FreeCAD are general-purpose desktop powerhouses. Pascal Editor is narrower and lighter: browser-native, WebGPU-rendered, local-first, and built from the start so both humans and AI agents can read and write the same semantic building model.
Watch the signal
Want the 30-second version? Watch the 30-second repo signal for Pascal Editor on Repomaniac. If you are new to the open source world, start with What Is Open Source? What Open Source Means, in Plain English. Read this article in Indonesian: Pascal Editor: CAD 3D Open Source yang Membiarkan Agen AI Merancang Bangunan.
*Sources: GitHub pascalorg/editor README, Pascal Editor official site, Repomaniac signal, October 30, 2026. Star and fork counts verified on GitHub on October 30, 2026.*