How to View CAD Files Online (Without Installing CAD)
Most “CAD viewing tips” recycle generic mouse shortcuts. This guide is the workflow procurement, quality, and engineers actually use: open → understand → measure → send a link.
The 4-step review loop
Online viewers (CADDaddy, 3DViewerOnline, Innerscene, and others) converge on the same loop. Learn it once:
- Step 1
Drop the file
STEP, STP, IGES, STL, OBJ… into the browser.
- Step 2
Orbit & isolate
Rotate, zoom, hide parts in the tree.
- Step 3
Measure or section
Check a size or cut through the solid.
- Step 4
Share a link
Send to a colleague — they open it without CAD.
1. Start with the right file
- Prefer STEP/STP for mechanical parts and assemblies. Ask suppliers for STEP before IGES when you can.
- IGES/IGS still shows up from mold/surface shops — openable, but noisier than STEP.
- STL is fine for print meshes; don't use it to “check CNC dimensions.”
- DWG is a different job — 2D drawings belong in LibreCAD/AutoCAD, not a 3D STEP viewer. CADDaddy does not open native DWG.
See STEP vs STL vs DWG if you're unsure what you were sent.
2. Navigate like you mean it
Browser CAD navigation cheat sheet
- Orbit / rotate
- Left-drag (or one-finger drag on touch)
- Pan
- Right-drag or middle-drag
- Zoom
- Scroll wheel / pinch
- Fit model
- Double-click empty space or Fit control
- Isolate a part
- Parts tree → click / hide siblings
Get oriented fast
Fit the model, then orbit around a recognizable feature (flange, shaft, logo face). If you feel lost, fit again — don't keep zooming into empty space.
Use the parts tree
Assemblies hide problems in sibling parts. Hide everything except the component you're checking, then turn neighbors back on to see interference or gaps.
3. Inspect: shaded, wire, section
Competitors' STEP viewers all push the same inspection trio. Use them in order:
- Shaded — overall shape, missing bodies, obvious wrong revision.
- Wireframe / edges — see through dense assemblies; spot open edges.
- Section plane — wall thickness, internal pockets, whether a bore goes through. (Section is a Pro tool in CADDaddy.)
60-second quality pass
- · Does the envelope match the quote / drawing?
- · Are critical holes / bosses present?
- · Any floating fragments or empty assemblies?
- · Units look sane? (mm vs inch mix-ups are common)
4. Measure with intent
Point-to-point measure answers “is this the 120 mm version or the 100?” Start with the live bounding-box L×W×H and the unit chip (STEP/IGES load in millimetres). Pro adds planar face area. It does not replace a CMM or a full drawing — use it for go/no-go checks, then send the link if the number is contractual. See the full walkthrough: measure a STEP online.
- Read bbox envelope before picking random corners
- Confirm units before you Slack a number upstream
- Screenshot or share the session so the number stays attached to the geometry
5. Share a review link (the underrated tip)
The highest-leverage habit: stop emailing 80 MB STEPs to people who only need to look. Upload once, send a link. Recipients open it on phone or PC with zero CAD licenses — the pattern every modern online viewer markets for a reason.
- Name the file so the link preview is readable
- Tell reviewers what to check (“confirm boss height”)
- Expect free shares to carry a watermark; clean external shares are a Pro concern
Large files & performance
Before open
- · Use Chrome or Edge (best WebGL / WASM)
- · Close heavy tabs — parsing STEP is CPU-heavy
- · Prefer a simplified export if the assembly is huge
While viewing
- · Hide unused parts in the tree
- · Avoid stacking section + heavy measure spam
- · If the tab dies, try a STEP AP203 “geometry only” export
Many browser viewers parse geometry locally with WebAssembly (OpenCascade-class stacks). Your file may never need to sit on a random server just to rotate — sharing is the step that uploads.
Practice on a real supplier file
Open CADDaddy, drop a STEP or IGES, and run the loop: fit → isolate → section/measure → share. Ten minutes beats another AutoCAD trial install.
Open a file free →FAQ
Can I view STEP on my phone?
Yes for review — orbit and pinch-zoom work. Measuring tiny features is easier on a desktop trackpad or mouse.
Is online viewing accurate enough for manufacturing?
Good enough for design review and go/no-go. Contractual dimensions still belong on the drawing / inspection plan.
Viewer vs full CAD — when do I stop?
Stop when you need to edit features, regenerate drawings, or run CAM. That's FreeCAD / Fusion / SolidWorks territory — see free AutoCAD alternatives.