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 Outdated schemas are automatically flagged by the validator.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

IFC Tips · 2026-06-03 · 9 min

IFC Coordinates Are Wrong: Survey Point, Base Point & Georeferencing Explained

You import the IFC and the building is two kilometres away — or sitting at the origin when it should be georeferenced to a national grid. Revit's three coordinate systems and IFC's georeferencing entities don't line up by default. Here's how to get the model where it belongs.

IFC Coordinates Are Wrong: Survey Point, Base Point & Georeferencing Explained — IFC Viewer Online article cover

Coordinate problems are some of the most disorienting IFC failures: the geometry is perfect, but the model is in the wrong place — far from the origin, offset from the other disciplines, or missing its real-world position entirely. The root cause is that Revit has three different origins and IFC has its own georeferencing entities, and nothing maps them together unless you make it.

Revit's Three Origins

Internal Origin

Revit's fixed internal (0,0,0). IFC import positions geometry relative to this — regardless of the other two points. This is why imported IFCs often land in the 'wrong' place.

Project Base Point

The project's local reference (e.g. a grid intersection). Used for setting-out dimensions within the design.

Survey Point

The real-world / geodetic reference that ties the model to a site or national grid. The basis for true georeferencing.

IFC4 Georeferencing Entities

Georeferencing is embedded in IFC4 via three entities working together. Get them right and any compliant tool can place your model on the planet.

IfcSite — carries the site's reference latitude, longitude, and elevation.
IfcProjectedCRS — declares the coordinate reference system (e.g. an EPSG code for a national grid).
IfcMapConversion — the transform (offset, scale, rotation) from the model's local engineering coordinates to the projected CRS.

Why Geometry Distorts Far From the Origin

When a model's local coordinates are huge — because someone modelled at true national-grid easting/northing values — 3D engines lose precision. Floating-point numbers have finite resolution; at coordinates in the millions, that resolution is coarse enough to make geometry wobble or jitter. The fix is to model near a local origin and carry the real-world position in IfcMapConversion, not in the geometry itself.

Getting It Right on Export

Set the Survey Point to the agreed real-world reference for the project.
Model near the Project Base Point / internal origin — not at true grid coordinates.
Export with Shared Coordinates / Site Placement set to shared.
For IFC4 / IFC4.3 deliveries, confirm IfcSite, IfcProjectedCRS, and IfcMapConversion are written and consistent.
Open the result and check the model sits where expected before delivery.

Check where your model actually sits

Open a model in the viewer and inspect its placement and spatial structure. Then load your own export to confirm it lands at the origin, not kilometres away.

IFC2x3 · 2.4 MB

Open the interactive IFC viewer

Coordinates are part of the broader quality picture — for the full pre-delivery framework see The Complete Guide to IFC Quality. And note that IFC 4.3 extends georeferencing significantly for infrastructure (roads, rail, bridges), where alignment and linear positioning add another layer on top of the entities above.

IFC Coordinates Are Wrong: Survey Point, Base Point & Georeferencing Explained