Computer-Aided Design (CAD) files are the lifeblood of architecture, engineering, and manufacturing industries. Formats like DWG and DXF are the industry standard for everything from skyscraper blueprints to mechanical part schematics. However, simply viewing these files has historically been a significant hurdle for non-engineers.

If you are a project manager, a contractor or a client, you probably do not have an AutoCAD licence just to look at a floor plan. You should not need one. With Online Document Viewer, running on the Doconut engine, a CAD drawing opens in your browser — free, with no account.

The Problem with Traditional "Free" Viewers

Often, when users search for a "free DWG viewer," they are met with a few subpar options:

Bloatware: Desktop applications that are technically free but come with huge installers, ads, or restricted features.
Inaccurate Rendering: Viewers that open the file but fail to display layers correctly, mess up font scaling, or ignore XREFs (external references).
Security Risks: Uploading intellectual property to untrusted, ad-supported free websites.

The Browser-Based Alternative

The Online Document Viewer renders the raw vector data of a CAD file on the server and sends your browser the result. The CAD viewer takes DWG, DXF and DGN, up to 10 MB per drawing, with no account and nothing installed.

What you actually get

1. Layer control

CAD drawings are built on layers — electrical, plumbing, structural. Layers switch off one at a time here, so the hatching or the services layer can come away from the walls underneath.

2. Measurement

Distance, angle and area, taken on the open drawing.

3. Rendering from the drawing data

Line weights, hatches and dimension text stay accurate at every zoom level, and title blocks stay legible at full zoom — because the render comes from the drawing data rather than from the low-resolution preview thumbnail stored inside the file. Multi-sheet files open a sheet at a time.

4. Three formats

DWG: the native AutoCAD format. Binary and closed.
DXF: the published text interchange version. Larger, readable by far more software, and the file to ask for when a DWG fails.
DGN: MicroStation, standard on civil, infrastructure and utilities projects.

Where the limits are

The CAD viewer accepts 10 MB per drawing. That is the number to plan around, and it is where most real drawing sets fail first. Before uploading:

PURGE unused blocks, layers and styles — it often halves the file.
AUDIT with fix errors on.
-WBLOCK out only the objects the recipient needs.
Save down to an older DWG version.

Do not convert to DXF to shrink it; DXF of the same drawing is bigger.

Two more things that are not in the file you send: xrefs and SHX fonts live on the sender's machine. A drawing that arrives sparse is usually complete and missing its attachments — ask for a bound copy (XREF, then Bind) rather than assuming the viewer dropped something.

What it does not do

It renders. Nothing here moves a line, changes a dimension or saves a revision. There is no account, so there is no permission model and no audit trail. There is no link to your open drawing to pass on: the upload belongs to one session and is deleted when it ends.

To hand a drawing to someone with no CAD software at all, the CAD converter exports DWG and DXF to PDF at up to 5 MB.

Powered by Doconut

The rendering comes from Doconut, a .NET library. For teams building their own engineering portals, that library is the licensed product — it embeds this same CAD viewing in a .NET application, running on your own servers. The website is not embeddable.

Conclusion

DWG, DXF and DGN in a browser, up to 10 MB, with layers and measurement, free and with no account.

Open the CAD viewer and drop a drawing on it.