Compare · two STEP files
Compare two STEP files and see what changed
Open the old revision of a part and the new one. PartCheck shows you every change between them — added material in green, removed in red — and writes the changes down as a list you can paste into a change order. It is free, it runs in your browser, and your files are never uploaded.
What it does for you
- Review a revision before you approve it. See what actually changed, not just what the email said changed.
- Catch the changes nobody meant to make — a hole that moved, a fillet that went missing, a wall that got thinner.
- Write the change order in seconds. Copy the list of changes and paste it straight into your ECO, your PLM or an email.
- Send it on. A PDF report anyone can read, without PartCheck and without CAD.
How to use it
- 1
Open both revisions
Drop the old revision and the new one onto the page — one at a time, or both at once.
- 2
See what changed
The two are laid over each other: green where material was added, red where it was removed, grey where nothing changed. Beside the part, the changes are written out in plain words; click one and the view zooms to it.
- 3
Look closer
Put the revisions Side by Side, drag a Split curtain across them, or Toggle between them by hand or on a timer. Cut a section, measure, or show the overall dimensions.
- 4
Hide the small stuff
When a revision touched many things, the Change Threshold slider hides the changes smaller than you care about, so the ones that matter stand out.
- 5
Share it
Download the comparison as a PDF, or copy the list of changes as text.
What you get
- The changes, in words
Written the way an engineer would: Hole Ø11.0 → Ø13.0 mm, 7 slots 14.0 → 18.0 mm long, New rib, 1.4 mm thick. Holes, bosses, fillets, slots, walls and ribs are named; matching changes are grouped into one line. And when it is true, the line people want most: Nothing else changed.
- The figures
How much material was added and removed, how much of the part changed, the largest single change, and a one-line verdict — from Practically identical through Minor change to Major redesign.
- A report
A two-page PDF with the overlay from the front and from below, each revision on its own, the verdict and a table of what changed.
Good to know
- Export both from the same place
PartCheck compares the two files as they were saved. Export both revisions from the same CAD document, or at least the same origin and orientation — a part that moved between exports shows as changed all over.
- STEP from any CAD system
SolidWorks, Fusion, Inventor, Creo, NX, CATIA, Onshape, Solid Edge and FreeCAD all export STEP (.step, .stp). STL meshes, IGES and native CAD files are not read: export the part as STEP.
- One part per file
A single part compares most clearly. Figures are in millimetres.
Questions
Is it free? Do I need an account?
Free, with no account and nothing to install.
Are my files uploaded?
No. Everything runs in your browser, on your own machine, and there is nowhere for the files to be uploaded to — which matters when the part is a client's.
How small a change can it find?
Changes down to about a twentieth of a millimetre. Smaller than that counts as unchanged.
Why does the whole part show as changed?
Almost always because it moved between exports — a different origin, or rotated. Export both revisions from the same coordinate system. If the two barely overlap, PartCheck says they look like different parts.
Can I send the result to someone who does not use PartCheck?
Yes: send the PDF, or paste the list of changes. Neither needs PartCheck or CAD to read.
Try it on a real part
The demo is a moulded enclosure lid in two revisions, drawn in CAD. It opens in the tool with no files needed — or open your own STEP files. Nothing is uploaded: the analysis runs in your browser.