CadNexa 3D April 14, 2026 6 min read

Free online STEP file viewer with BOM generator and weight calculator — no installation needed

If you've ever needed to quickly check a STEP file, calculate the weight of a part, or generate a bill of materials — you know the pain. Desktop CAD software needs expensive licenses. Cloud-based tools need heavy downloads and accounts. Open-source alternatives are slow and complex to set up. And none of them give you a quotation at the end.

What if you could open any 3D CAD file directly in your browser, see the BOM with material costs, and generate a professional quotation — all in under 2 minutes? That's what CadNexa does.

📸 Screenshot: CadNexa 3D with a loaded STEP assembly showing parts tree and BOM
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What is CadNexa 3D?

CadNexa 3D is a browser-based 3D CAD viewer built specifically for manufacturing professionals in India. It opens STEP, IGES, BREP, STL, OBJ, GLB, FBX, 3MF, and 10+ other formats directly in your Chrome, Edge, or Firefox browser. No download. No license. No installation.

But it's not just a viewer. It's a manufacturing workflow tool that does what no other viewer does:

Auto-generates Bill of Materials (BOM) — detects all parts, calculates volume and weight
Indian material pricing database — SS304, EN8, Aluminium 6061, Brass IS319 and 25+ materials with current market prices in ₹/kg
3D measurement — point-to-point distance, edge length, face area, angles
Quotation builder — material cost + overhead + profit + GST = professional PDF quote
Cost estimator — add machining, turning, grinding operations per part
Exploded view and section cuts — understand assembly relationships
2D drawing export — SVG, PNG, PDF, DXF from 3D model

    Who uses CadNexa 3D? Plant heads preparing quotations, purchase managers verifying vendor submissions, design engineers reviewing supplier parts, estimation teams calculating material costs, and CNC shop owners checking customer files before accepting orders.
  

How to open a STEP file online — step by step

Step 1: Go to CadNexa

Open cadnexa.com in your browser. Sign in with Google (one click, free forever).

Step 2: Click "Open" and select your file

Click the green Open button and browse to your STEP, IGES, or STL file. The model loads in seconds. Supported file types:

Format	Extensions	Source
STEP	.step, .stp	All major CAD software
IGES	.iges, .igs	Legacy CAD systems
BREP	.brep, .brp	Open-source CAD tools
STL	.stl	3D printing, mesh models
OBJ	.obj	General 3D models
GLB/GLTF	.glb, .gltf	Web 3D, AR/VR
FBX	.fbx	3D animation, game engines
3MF	.3mf	Modern 3D printing
DXF	.dxf	2D/3D drafting software
And more...	.dae, .sat, .amf, .ply	Various CAD systems

Step 3: Navigate the 3D model

Use your mouse to interact with the model: left-click and drag to rotate, scroll to zoom, right-click and drag to pan. On mobile devices: swipe to rotate, pinch to zoom. The parts tree on the left shows all components — click any part to select and highlight it.

📸 Screenshot: 3D model with parts tree expanded and a part selected
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Auto-generate BOM with weight and material cost

This is where CadNexa goes beyond a simple viewer. Click the BOM button in the toolbar, and CadNexa automatically:

Detects every part in the assembly
Calculates the exact volume using OpenCascade geometry kernel
Assigns a default material (you can change it)
Calculates weight: Volume × Density
Calculates material cost: Weight × Price per kg

The material database includes 30+ Indian engineering materials with current market prices:

Material	Grade	Density (kg/m³)	Price (₹/kg)
Stainless Steel	SS304	8000	₹220
Mild Steel	IS2062 E250	7850	₹65
EN8	C45	7850	₹85
Aluminium	6061 T6	2700	₹280
Brass	IS319	8500	₹520

    Why this matters: A purchase manager receiving a vendor quotation can instantly verify if the quoted weight and material cost are reasonable. A plant head can generate an accurate cost estimate before committing to a customer quote. No spreadsheets, no manual calculations.
  

Measure dimensions directly on the 3D model

Click Measure in the toolbar, then click any two points on the model. CadNexa shows the exact distance in millimeters with dimension lines. You can also measure edge lengths, face areas, and angles between surfaces.

On mobile, the measurement tool works with touch — tap two points and the distance appears. This is particularly useful on the shop floor when you need to quickly verify a dimension without opening CAD software.

Generate professional quotations with GST

Click Quote to open the quotation builder. Enter your overhead percentage, profit margin, and GST rate. CadNexa calculates the final quotation amount automatically:

Material Cost + Overhead % + Profit % + GST % = Professional Quotation

Generate a PDF quotation with your customer's name, quote number, validity, delivery terms, and payment conditions. Send it to your customer within minutes of receiving their enquiry.

File size limits — what to know

CadNexa processes 3D files entirely in your browser using WebAssembly. This means your files stay private — but it also means your device's RAM is the processing power. Here's what to expect:

File Size	Performance	Recommended Device
Under 10 MB	Instant — loads in 2-5 seconds	Any device, including phones
10 — 30 MB	Fast — loads in 5-15 seconds	Any laptop or desktop
30 — 50 MB	Moderate — 15-30 seconds, may use high RAM	Desktop with 8GB+ RAM
50 — 100 MB	Slow — 30-90 seconds, needs patience	Desktop with 16GB+ RAM
Over 100 MB	May crash or freeze	Consider splitting the assembly

    Tip for large files: If your STEP file is over 50 MB, try opening it on a desktop computer with Chrome. Close other browser tabs to free up RAM. If it still crashes, split the assembly into sub-assemblies in your CAD software and open each one separately.
  

Works on mobile — check weight on the shop floor

CadNexa is fully responsive. On your phone, you get a clean interface with four essential buttons: Open, Measure, Weight, and BOM. No cluttered desktop interface squeezed onto a small screen.

Install CadNexa as an app on your Android phone — open cadnexa.com in Chrome, tap the menu, and select "Add to Home Screen." It opens full-screen like a native app.

Your files stay private

CadNexa processes everything in your browser using WebAssembly technology. Your STEP files and engineering data never leave your computer. We don't upload, store, or see your design files. This is fundamentally different from cloud-based viewers that upload your files to their servers.

Try CadNexa 3D — free forever

Open your first STEP file in 10 seconds. No download, no credit card, no installation.

Open CadNexa 3D →

Frequently searched questions

How to open a STEP file without expensive CAD software?

Go to cadnexa.com, sign in with Google, click Open, and select your .step or .stp file. It opens instantly in your browser — no expensive license needed.

How to calculate the weight of a 3D model?

CadNexa automatically calculates weight when you open a STEP file and click BOM. It uses the exact volume from the 3D geometry multiplied by the material density. Assign the correct material (SS304, EN8, etc.) and the weight updates instantly.

Is there a free online BOM generator?

Yes. CadNexa generates BOM for free from any STEP or IGES file. It detects all parts, calculates volume, weight, and material cost using Indian market prices. No paid license required.

How to create a manufacturing quotation quickly?

Load your STEP file in CadNexa, click BOM to get material costs, click Quote to add overhead, profit, and GST. Generate a PDF quotation in under 2 minutes.