DWG

AutoCAD Drawing

image/vnd.dwg Released 1982 · by Autodesk

The image/vnd.dwg MIME type represents the DWG file format, a proprietary binary file format used for storing two- and three-dimensional design data and metadata. Maintained primarily by Autodesk, it is the native format for AutoCAD and one of the most widely used formats in the Computer-Aided Design (CAD), engineering, and architecture industries.

CAD & Vector Graphics Transparency Production Ready

Technical Specifications

MIME Type

image/vnd.dwg

Extensions

.dwg

Container

DWG Binary Container

Compression

Proprietary Binary Compression (LZ77 based in newer versions)

Algorithms

Proprietary (Autodesk ObjectDBX)

Color Depth

Vector (True Color / Indexed AutoCAD Color Index)

Metadata

None

Capabilities

Transparency

Animation

Progressive Loading

Alpha Channel

HDR Support

Official Specification

Aliases: application/acadapplication/x-acadapplication/autocad_dwgimage/x-dwgapplication/dwgapplication/x-dwgdrawing/dwg

Magic Bytes & HTTP Headers

File Signature (Magic Bytes)

41 43 31 30 (AC10)

ASCII: AC10

HTTP Headers

Content-Type: image/vnd.dwg

HTML Accept Attribute

accept="image/vnd.dwg, .dwg"

Browser Support Matrix

Browser	Status	Min Version
Chrome	Not Supported	—
Firefox	Not Supported	—
Safari	Not Supported	—
Edge	Not Supported	—
Internet Explorer	Not Supported	Legacy

Advantages & Limitations

Advantages

The undisputed industry standard for 2D drafting and basic 3D CAD modeling
Highly optimized binary structure keeps file sizes relatively small compared to text-based CAD formats like DXF
Supports incredibly complex datasets including external references (XREFs), dynamic blocks, and extensive custom metadata

Limitations

It is a closed, proprietary format, making it difficult for third-party developers to support fully without licensing the Open Design Alliance (ODA) SDK
Lacks native web or standard operating system previewer support
Format versions change frequently (roughly every 3 years), breaking backward compatibility for older CAD software

Developer Code Snippets

import magic
# Note: Due to its proprietary nature, many magic databases identify DWG files with the generic 'application/x-dwg' or 'image/vnd.dwg'
print(magic.from_file('floorplan.dwg', mime=True))

const FileType = require('file-type');
const type = await FileType.fromFile('floorplan.dwg');
console.log(type?.mime); // Usually outputs 'image/vnd.dwg' or undefined depending on the library version

import "net/http"
// Manually sniffing the DWG header:
// isDWG := bytes.HasPrefix(buf, []byte("AC10"))

$mime = mime_content_type('floorplan.dwg');
echo $mime; // Resolves based on the server's magic.mime file configuration

File Detection Steps

How to programmatically detect a image/vnd.dwg file by reading its raw bytes:

1 Check the first 4 bytes for the ASCII signature 'AC10' (Hex: 41 43 31 30)
2 Read the following two bytes to determine the specific AutoCAD version format (e.g., '15' for AutoCAD 2000, '32' for AutoCAD 2018)

Software Support

A

AutoCAD

A

Autodesk DWG TrueView

B

BricsCAD

D

DraftSight

F

FreeCAD (via ODA Converter)

Conversion Tools

Share & Embed

Markdown Badge

[![DWG Format](https://freewebptojpg.com/mime/image/dwg/badge.svg)](https://freewebptojpg.com/mime/image/dwg)

Interactive iframe Widget

<iframe src="https://freewebptojpg.com/mime/image/dwg/embed" width="100%" height="280" style="border:1px solid #cbd5e1;border-radius:8px;" title="DWG Specs"></iframe>

JSON API

All data on this page is available as a free, open JSON API. Use it in your project, documentation, or tooling.

GET https://freewebptojpg.com/mime/image/dwg.json Open JSON

Free to use

No auth required

CORS enabled

Use from any domain

Cached 24h

Cache-Control headers set

Frequently Asked Questions

What is the difference between DWG and DXF?

DWG is a closed, proprietary binary format optimized for smaller file sizes and fast loading within AutoCAD. DXF (Drawing Exchange Format) is an open, ASCII-based (or sometimes binary) format designed for interoperability and sharing CAD data across different software applications.

Can web browsers open DWG files?

No modern web browser natively supports the DWG format. To display DWG files on the web, developers must convert them to a web-friendly vector format (like SVG or PDF) on the server, or use a client-side WebGL/Canvas renderer like the Autodesk Forge Viewer.

What are the magic bytes for a DWG file?

All DWG files begin with a 6-byte version string starting with 'AC10', which translates to the hex values 41 43 31 30. For example, AutoCAD 2018 files start with 'AC1032'.