Free 3D viewer / STEP
Free online STEP viewer
Open .step and .stp files right here, with no CAD software and no sign-up. Assemblies keep their part names and colours, so you can hover a part to read its name, switch to X-ray to see inside, and measure a gap.
See a STEP assembly as your client would, with its drawings: Open a sample review
What you can do with it
Everything a CAD reviewer needs, in the browser
The toolbar on the left of the viewer has the tools you’d otherwise open your CAD program for. They work the moment your file opens.
Parts listP
Every part by the name it has in the file. Search, hide one, or show it on its own.
Section cutS
Cut through the model along X, Y or Z to check what's inside a housing.
Exploded viewE
Spread the parts apart, from the centre or along one axis, to see how it goes together.
MeasureM
Click two points for the distance between them, at the model's real size.
X-ray, wireframe, clayX
See through the outer parts, check the mesh, or look at the shape without colours.
Pin a note
Click a spot and type. The note keeps the angle you were looking from.
Send it on
Need someone else to look at it? They don’t need CAD either
- 1
Open it here
Drop the STEP file on the viewer above.
- 2
Pin your questions on it
Click the part you mean and type: “Is this wall thick enough?”
- 3
Click Share
Copy a review link, or we email it for you. Sharing needs a free account, and your model and notes come with you.
- 4
They answer on the model
Your client or supplier opens the link in any browser, with no account, and clicks the spot to reply. You get an email.
- See a sample review →Start free
Who uses it
Made for people who get sent STEP files
Mechanical engineers
Show a design to a manager, client or buyer who has no CAD licence, and get their notes on the parts.
Section cutMeasureMachine shops and suppliers
Check a customer's part before you quote: sizes, holes, what's hidden inside. Ask about a feature right on it.
Parts listX-ray3D print services
Open what a customer sent, check its size and walls, and send back what needs changing before printing.
MeasureNotesProduct and freelance designers
Send each round to the client as a link, collect every comment in one place, and get a clear sign-off.
Review linksVersions
What’s free
The viewer is free. A free account lets you send it
| Feature | Viewer, no account | Free account |
|---|---|---|
| Open STEP, IGES, Rhino, STL, OBJ, FBX, GLB and more | ✓ | ✓ |
| Parts list, section cut, exploded view, measure, X-ray | ✓ | ✓ |
| Pin notes on the model for yourself | ✓ | ✓ |
| Send a review link, and the client replies with no account | – | ✓ |
| Keep your models and every note in one place | – | 3 new every 30 days |
| Email when the client opens the link or leaves a note | – | ✓ |
| Versions, compare and client sign-off | – | On paid plans |
No install, no account
Works in Chrome, Edge, Safari and Firefox, on Windows, Mac and Linux.
Your file stays private
Most files are read in your browser. Very large CAD files are converted on our server and deleted straight after.
Real size and parts
Assemblies keep part names, colours and real-world dimensions.
Up to 1 GB
Big assemblies open too. A cut-off STEP file opens with the part that's there.
How to open a STEP file
- 1Drop your .step or .stp file on the viewer above, or click it to choose one.
- 2Turn it with the mouse. Use the toolbar for wireframe, X-ray, part names, measuring and lighting.
- 3Click Share to send it to a client: they open one link and click the spot they want changed.
About STEP files
STEP (ISO 10303) is the standard way to move solid models between CAD programs: SolidWorks, Fusion 360, Inventor, CATIA, Creo, Onshape and FreeCAD all export it.
- Export solids, not just surfaces: a STEP with only curves or wireframe has nothing to show.
- AP214 or AP242 keeps part colours; AP203 often comes through grey.
- Send the whole assembly as one STEP file, or several part files together in one .zip.
- Large assemblies, up to 1 GB, are converted on our server when they're too heavy for a browser.
Questions
STEP files, answered
Can I open a STEP file without CAD software?
Yes. Drop the .step or .stp file on the viewer above. It's converted into a mesh you can orbit, section with X-ray, measure and share, all in the browser.
Why does my STEP file open blank?
Usually the file holds only curves, sketches or a wireframe, with no solid or surface geometry. Export it again with solids or bodies selected, or try AP214 instead of AP203.
Can I send the model to a client for feedback?
Yes. Once it's open, click Share in the top-right corner of the viewer and choose Copy a review link or Send it by email. You create a free MeshMarkup account on the way, and the model comes with you.
Your client opens the link in any browser with no account and nothing to install, clicks the exact spot they want changed, and the note stays pinned there with the camera angle they were looking from.
Is my file uploaded anywhere?
Most files are read and converted right in your browser and never leave your computer. Very large CAD and mesh files are converted on our server instead, then deleted straight after the converted model is sent back to your browser. Nothing is kept unless you choose Share.
Get feedback on the model, not on a screenshot
One link, no sign-up for your client, and every note pinned to the spot it’s about.