When the building exists, but the BIM doesn't.
Free · edit without signing up · open format
- Draw. Walls, doors, windows, slabs, columns, ducts and pipes on 2D plans, with a live 3D view.
- Ask. Give the AI agent a floor plan, a site photo or a description. It writes the model and renders it to check its work.
- Query. Plain CSV and GeoJSON underneath: query it with SQL, export IFC, glTF, DXF or PDF.
Open an example · Sign in for the AI agent · 中文
For buildings that never had BIM.
Design tools assume a blank page. BimDown starts from what is already standing: an old plan, a few photos, a tape measure.
- Retrofit and renovation Document the building before you change it: walls, openings, rooms, and levels, ready to measure and discuss.
- Facility management A queryable model of a building you inherited: rooms and areas, equipment, and routes, searchable with SQL.
- Energy modeling Rooms, envelope walls, windows, slabs, and roofs as clean geometry, a starting point for an energy model instead of weeks of hand entry.
Start from an example
Plain BimDown models, fully editable. Click one to open it in the editor.
- Small office: 2 storeys, ~600 m² a floor: open offices, meeting rooms, stair and WC core, columns, beams, roof.
- Apartment building: 3 storeys, two 3-bedroom apartments per floor around a stair core, with balconies.
- Plant room and office (MEP): AHU, chiller, pumps and a rooftop cooling tower; supply, return and outdoor air ducts and chilled and condenser water pipes, connected to diffusers in the office.
Use the agent you already have.
A BimDown model is a folder of plain files, so any coding agent can work on it locally with the open-source CLI. No account needed.
npm install -g bimdown-cli · Full setup guide on GitHub
What BimDown is not
- Not a Revit replacement. Detail stops around LOD 200: what, where, and how big.
- No families or type catalogs, no MEP fittings, no complex stairs (spiral or winder).
- No construction documents, detailing, or structural and MEP calculations. No IFC import.
Common questions
What is BimDown?
Two things with one name: an open file format for lightweight building models (CSV attributes plus GeoJSON geometry, one folder per level), and BimDown Studio, a web app with a browser editor and an AI agent that builds models from drawings, photos, or text.
Is it free? Do I need an account?
Yes, it is free. The editor works without an account and keeps your draft in the browser. A free account adds cloud projects, share links, and the built-in AI agent, which has a daily limit per user.
Can I use my own AI agent?
Yes. Install the CLI with npm install -g bimdown-cli and add the BimDown skill. Agents such as Claude Code, Codex, or Cursor can then create, validate, render, and query models on your machine, with no account.
Does it work with IFC and Revit?
BimDown exports IFC, glTF, DXF, and PDF. Revit 2025 and later round-trips through the open-source add-in. IFC import is not supported.
Is the model good enough for energy modeling?
It captures the geometry an energy model starts from: rooms, envelope walls, windows and doors, slabs, and roofs. Thermal properties such as U-values and schedules are not in the format yet, and AI-built models should be checked against the source drawings.
Where is my data stored?
Without an account, the editor keeps your draft in this browser only. Cloud projects are stored on Cloudflare. Any project exports as a .zip of plain files, so you can take it with you at any time.
BimDown is part of JouleDown