Compare IFC Files

Compare two IFC models by GlobalId and see what was added, deleted, moved, or unchanged in a visual viewer.

Compare two IFC models and see what changed. Upload both, and every element is matched by GlobalId and classified as added, deleted, moved or unchanged — with the result shown in a 3D viewer you can walk through rather than as a list of identifiers.

"What's different in this revision?" is asked on every project, every week, and answered by opening two models side by side and looking. That finds the obvious changes and misses the one that matters: the beam that moved 200 mm, the door that quietly disappeared, the wall type that changed on one floor. A comparison keyed on element identity finds all of them, including the ones nobody thought to look for.

When to reach for it: When you need to see what changed between two versions of a model — a site progress update, a design revision, or before/after a coordination sprint.

What you get: An interactive 3D comparison viewer that colour-codes every element into four categories: added (green), deleted (red), moved (orange), unchanged (grey). Elements are matched by GlobalId; moved elements are detected via position change.

Example: Compare last week's model against today's to review progress.

Matched by identity, not by geometry

The comparison works on GlobalIds — each element's permanent identifier. That is what makes it reliable: an element that moved is recognised as the SAME element in a new position, rather than as one deletion plus one addition. Geometric comparison can't make that distinction, and a change report that turns every move into a delete/add pair is unreadable on a real revision.

It also means the comparison depends on identifiers being stable and unique. Two things break it, and both are worth checking first with the Schema & Identity Check: duplicate GlobalIds, which make the matching ambiguous, and a re-export that regenerated every identifier, which makes the two revisions look like completely different buildings. If the second has happened, no tool can produce a meaningful diff — the information is gone.

Four categories, in 3D

Added — in the new model, not in the old. New scope, or an element that was previously modelled somewhere else.
Deleted — in the old, gone from the new. The category worth reading most carefully: unintended deletions are the changes least likely to be noticed any other way.
Moved — same element, different position. Where coordination problems come from, and invisible in a side-by-side comparison unless you already suspected it.
Unchanged — everything else, which is most of the model, and which is what makes the other three readable.

Reviewing the result

The results render in the viewer with the categories distinguished, so a revision review becomes navigating the actual building rather than cross-referencing GlobalIds in a spreadsheet. That's the difference between a diff someone reads and one that gets filed.

Because both models are uploaded together, the tool's file picker takes two files at once — pick the baseline and the revision in one selection. For change tracking over time rather than between two files, a workspace model keeps its versions, so you can compare any revision against any other without hunting for the files. And when a change needs raising with whoever made it, findings can become BCF issues.

How to compare two IFC files

Upload your primary IFC file (the newer version)
Upload a second IFC file to compare against (the older version)
Click Run to analyse element GlobalIds and positions
The 3D viewer opens with elements coloured by category
Use the four filter buttons to show only added, deleted, moved, or unchanged elements

Under the hood

BIMCamel parses IFC files in the browser using the open-source web-ifc engine and renders models with @thatopen/components + three.js. Heavy operations (clean / optimise / validate / convert) run on disposable server-side workers using the same web-ifc stack plus our own .NET pipeline; results stream back to your browser as soon as they're ready. Uploads sit on our servers only as long as your tier's retention window allows and are never used to train AI.

Frequently asked questions

How do I see what changed between two IFC revisions?

Upload both models here. Every element is matched by GlobalId and classified as added, deleted, moved or unchanged, and the result is shown in a 3D viewer you can walk through rather than as a list of identifiers.

How does it detect that an element moved rather than being replaced?

By matching on GlobalId — the element's permanent identifier. It's recognised as the same element in a new position, instead of one deletion plus one addition. Geometric comparison can't make that distinction, and the resulting report is unreadable on a real revision.

Why does everything show as added and deleted?

Because the GlobalIds changed between the two files — usually a re-export that regenerated them, or a repair run with identifier regeneration enabled. Once identity is gone, no tool can produce a meaningful diff. Run the Schema & Identity Check on both files to confirm.

Can I compare versions of a model in my workspace?

Yes — a workspace model keeps its version history, so you can compare any revision against any other without going to find the files. Uploading two files directly is for one-off comparisons.

What should I look at first?

Deletions. Additions and moves are usually intentional and often discussed; an element that quietly disappeared between revisions is the change least likely to be noticed any other way, and the most expensive to find on site.

Which IFC versions are supported?

IFC2x3 and IFC4 — the two schema versions exported by essentially every AEC authoring application. IFC4x3, the infrastructure schema, works too: it opens in the viewer, and validation, health reports, property-set editing and georeferencing all run on it. Tools that need geometry processing, such as clash detection and 3D export, aren't verified on IFC4x3 yet.

What's the maximum IFC file size?

Up to 25 MB as a guest, 100 MB with a free account, 500 MB on Pro, and 1 GB on Team. The caps are on upload size only — every tool itself is available on every tier.

What happens to my file after processing?

Your file is uploaded over HTTPS and processed on our servers. Guest uploads are stream-only — the working files are deleted as soon as your download finishes. Free accounts keep results for 7 days; Pro keeps them 90 days and Team 180 days. Files are never shared with third parties or used to train AI.

Is Compare IFC Files free?

Yes. Compare IFC Files is free to use — guests get 3 runs a day with 25 MB uploads, and a free account raises that to 10 runs a day with 100 MB uploads. No trial clock, no watermarks.