What CAD Compare finds
Two versions of a STEP file in, the differences out: in words and in 3D. Everything runs in your browser.
What it finds
Changed features, in words
“Through hole Ø6 → Ø6.5”, “fillet R2 → R3”, “chamfer added”, “length 80 → 90 mm”. Holes, counterbores, fillets, chamfers, bosses, pockets and keyways are recognised by name.
Same part, different position
Parts that were only moved or rotated are recognised as the same shape, with the offset and angle.
Mirrored parts
Left-hand and right-hand versions of a part are recognised as mirror images instead of “different”.
Unit mistakes
If two files differ by exactly a factor of 25.4, you are told that one of them probably has the wrong unit (inch vs. mm).
Assembly changes
Parts added, removed, renamed or replaced, changed quantities, moved parts, new sub-assemblies, and what changed in each modified part.
Duplicates in a folder
Batch comparison: which files in a set are the same part, and what changed between an old and a new set of files.
How it works
- Choose two STEP files: version A and version B of a part or an assembly (.step / .stp, from any CAD system).
- The comparison runs in your browser. The geometry engine (OpenCascade) is loaded into the page; your files are not uploaded anywhere.
- Read the verdict: identical, the same part in another position, or different. The differing faces are coloured in the 3D view.
Use it from your AI assistant
Claude, Cursor and other assistants that support MCP can compare your CAD files directly: “Compare bracket_v1.step and bracket_v2.step and tell me what changed.” The comparison runs locally on your computer, like in the browser.
Questions
Are my CAD files uploaded?
No. The comparison runs in your browser (or, with an AI assistant, in a program on your computer). Our server only handles your account and subscription; it never receives CAD files. Only if you share a result as a link, the result and a 3D mesh of the parts are uploaded, after you agree, and never the STEP files. When you report a wrong result, you can choose to attach the two files; they are deleted after 90 days.
Which files can I compare?
STEP files (.step, .stp; AP203, AP214 and AP242) of single parts, assemblies and (with Pro) multi-body parts, exported from any CAD system. Native formats such as SolidWorks or Fusion files, drawings (PDF) and meshes (STL) are not supported.
How exact is the comparison?
Surfaces are compared point by point with exact distances. The tolerance is chosen from the size of the part (about one ten-thousandth of its diagonal) and shown with the result. Please check results that matter for production against the CAD models.
Which browsers work?
Current versions of Chrome, Edge, Firefox and Safari. Large parts need a few seconds and enough memory; on computers that run CAD software this is usually no problem.
Do I need an account?
Not for comparing two single parts. For everything else (the list of differences, assemblies, batch comparison, reports, AI assistants) you sign in with an e-mail code, Microsoft or Google; no password. During the beta, all of it is free.
Who makes this?
CAD Compare is made by WANSU UG (haftungsbeschränkt), Germany.