Is my IFC file uploaded anywhere?

No. Files are parsed entirely in your browser via web-ifc, a WebAssembly build of the open-source IFC parser. Nothing leaves your machine. The app works completely offline once loaded.

Can I use it with confidential models under NDA?

Yes. Because all processing happens in your browser and no data is ever transmitted to any server, you can safely use it with confidential project models under NDA. There is no service agreement to review with your client — no data changes hands.

Can I share the validation results with my team or client?

Yes. After running validation, click Share Report to copy a link that encodes the full Health Score and issue list directly in the URL — no file upload, no server, no account required. You can also export results as JSON, CSV, or a Validation Certificate. The IFC file itself never leaves your browser.

Yes, fully. IFC Viewer Online works on any modern browser — Chrome, Edge, Firefox, and Safari on both Mac and Windows. No plugin, no installation, no operating system restriction.

What happens if my IFC file is very large?

The app handles files up to 2 GB. Performance depends on your device — files under 200 MB load well on most modern hardware. Once parsed, geometry is cached in OPFS so every subsequent load of the same file is instant, even offline.

How does the validation work?

The validator runs 44 built-in rules in a background Web Worker so the UI stays responsive. Rules cover GUID duplicates, spatial hierarchy, orphan elements, naming conventions, missing type assignments, ISO 19650 property sets, LOD completeness, clash detection, proxy overuse, coordinate offset, storey-elevation integrity, unit consistency, and more. You can also run a buildingSMART IDS specification against the model. Every model receives a Health Score from 0 to 100. Results stream in as each rule completes.

Can I fix errors and re-export a corrected IFC?

Yes. All edits (GUID fixes, renames, property value changes) are held as non-destructive diffs with full undo/redo. Clicking Export IFC applies all diffs to the original binary in a Web Worker and downloads the corrected file — no server involved.

What IFC versions are supported?

IFC2x3, IFC4, IFC4x1, and IFC4x3. The viewer uses the open-source web-ifc parser — the same engine used by most modern BIM tools and @thatopen/components. Outdated schemas are automatically flagged by the validator.

What measurement tools are available?

You can measure lengths between any two points, areas of surfaces, volumes of enclosed elements, and individual edge lengths — all directly in the 3D viewport. Measurements persist as labelled annotations and can be exported alongside your model.

Can I load multiple IFC files at once?

Yes. Load as many IFC files as your device memory allows. Each model has independent visibility, transforms, validation, quantity takeoff, and export. Use the Scene panel to manage, reorder, or remove models at any time.

Does it work offline?

Yes, once the page is loaded. The WebAssembly parser and WebGL renderer run entirely in the browser. Parsed geometry is cached in OPFS so repeat loads are instant even without a network connection.

What are the file size limits?

There is no enforced limit — performance depends on your device. Files up to ~200 MB typically load well on modern hardware. The OPFS geometry cache means you only pay the parse cost once per file.

Is it free? Can I use it for commercial projects?

Yes, completely free. The source code is MIT-licensed. You can use the live app or fork the repository for your own projects, including commercial ones.

Back to the BIM & IFC blog

Best Practices · 2026-06-04 · 7 min

Can You Use an Online IFC Viewer with Confidential Project Data?

The NDA in your project contract doesn't care which software you use. Before opening a sensitive IFC in any online tool, here's the technical test that tells you — in 30 seconds — whether your data stays on your machine.

Can You Use an Online IFC Viewer with Confidential Project Data? — IFC Viewer Online article cover

0 bytes — of your IFC file uploaded
100% — processed in your browser
0 — server connections for model data
30s — to verify it with DevTools

The question every BIM coordinator asks before opening a confidential file in an unfamiliar online tool: does this thing upload my model somewhere? If the answer is yes — and for most cloud-based BIM viewers, it is — then your NDA, your client confidentiality obligations, and your firm's data policy all have something to say about it.

This post gives you the technical answer for IFC Viewer Online, plus a 30-second DevTools test you can run yourself to verify it independently.

The Core Question: Does 'Client-Side' Actually Mean Client-Side?

Browser-based tools split into two categories. The first uploads your file to a vendor server, runs the processing there, and streams results back to your screen. The second does everything inside your own browser tab — the WebAssembly runtime executes on your own hardware, accessing only your own RAM and local storage.

IFC Viewer Online belongs to the second category. Your file is parsed by web-ifc — an open-source IFC parser compiled to WebAssembly — running directly in your browser process. The parsed geometry lives in your browser's memory and OPFS (Origin Private File System), a sandboxed local area no other site or server can touch. Not one byte of your model is transmitted anywhere.

What Never Leaves Your Device

The IFC file binary — not a single byte transmitted
Model geometry, coordinates, and spatial structure
All IfcPropertySets and element properties
Element names, descriptions, and GlobalIds
Parsed geometry cached to OPFS — local, sandboxed, invisible to any server
Edits (GUID fixes, property changes) until you explicitly export the corrected file

What Does Go Outside Your Browser (and Why It's Safe)

Anonymous analytics events via PostHog: "file opened", "validation ran", "export clicked". No model content, no filenames, no property values — verifiable in DevTools.
Your email address — only if you voluntarily submit the footer subscription form.
A validation issue summary — only if you click Share Report. The URL encodes Health Score and issue list, not model geometry. You control when and whether to share.

Three NDA Scenarios — What the Rules Say

Scenario 1: You're reviewing a client's model under NDA

You've received an IFC from a client under NDA. You want to run a health check before a coordination meeting. Because the model is processed entirely in your browser, there is no data transfer event that would implicate the NDA. The model never leaves your machine — you're using your browser as a local analysis environment, not a cloud service.

Scenario 2: You're a subcontractor validating before CDE submission

You're preparing to upload an IFC to a project CDE. Before submission, you validate it locally. No upload, no server, no issue. The CDE upload happens from your authoring tool to the CDE platform. The validator is a local step that precedes it.

Scenario 3: You want to share the validation report with your team

The Share Report feature encodes the issue list (rule violations, counts, model name) into a URL rendered by a Cloudflare Worker. This is opt-in — you choose when to share. The URL contains issue summaries, not model geometry. If your NDA covers issue summaries, skip Share Report and export a PDF screenshot instead.

IFC Viewer Online

IFC processed 100% in browser (WebAssembly)
Zero bytes of model data transmitted
No account, no login required
No Data Processing Agreement needed
Works offline once loaded
Open-source — fully auditable on GitHub

Cloud-based BIM viewers

Upload model to vendor servers for processing
Model stored in vendor data centres
Account required (identity tied to uploads)
DPA required for GDPR Article 28 compliance
Internet connection required every session
Closed source — no audit possible

The 30-Second DevTools Verification

Open Chrome or Edge. Navigate to the viewer.
Press F12 → Network tab → filter by "XHR" or "Fetch".
Drag your most sensitive IFC file into the viewer and wait for it to load.
Inspect every request in the panel. You will see PostHog analytics events (no model content) — and nothing else.
Clear the filter and check "WS" (WebSocket) — none will open for model data.

If you need a written record of this for a security review, the full Privacy Policy documents every data flow, and the MIT-licensed source code on GitHub is fully auditable.

There is no service agreement to review with your client — no data changes hands.
IFC Viewer Online FAQ

Can You Use an Online IFC Viewer with Confidential Project Data?