How to open a DXF file without AutoCAD

A DXF file usually comes from someone else: an engineering office, a laser cutting service, an online shop for parts. And there you are without any CAD software. This page explains what is inside such a file and how to look at it.

What is a DXF file?

DXF stands for Drawing Interchange Format and comes from Autodesk, the makers of AutoCAD. It is meant as an exchange format: a drawing should travel from one CAD program to another without both having to speak the same native format.

The content is almost always a two-dimensional drawing: lines, arcs, circles, polylines, dimensions and text. All of it sits on layers, and every layer has a colour. Those layers are the reason a DXF is more than a picture - you can hide individual ones, for example to remove the dimensions and see only the outline.

Most DXF files are plain text. You can open one in a text editor and will read numbers in a strict sequence of group code and value. That is rarely useful, but it explains why DXF files are often surprisingly large for what they contain.

Which programs open a DXF?

You do not need AutoCAD. These options work:

• Cubory - the viewer this page belongs to. Shows DXF with layers and original colours, runs on Mac, Windows and Linux, costs nothing and needs no account.
• LibreCAD or QCAD - free CAD programs. They can also draw and edit, which makes them heavier and less obvious to operate.
• Online viewers - quick, but the file ends up on someone else’s server. For drawings that belong to a client, that is often a bad idea.
• Autodesk software - AutoCAD itself or the vendor’s free viewer. Both far heavier than necessary if you only want to look inside.

Viewing a DXF with Cubory

1. Download and install Cubory - there are installers for macOS, Windows and Linux.
2. Open the file by double-clicking it or drag it into the window. The first time, your system may ask which program is responsible.
3. The layer list is on the left. Clicking the dot next to a layer hides it, for example the dimensions.
4. Zoom with the scroll wheel, pan with the left mouse button held down. Fit brings the whole drawing back into view if you got lost.

When nothing shows up

A drawing that looks empty usually has one of four causes:

• Everything is there, just far away. Some programs place objects a long way from the origin. Press Fit once.
• The layer is hidden. Check the layer list to see whether all dots are on.
• Dark colours on a dark background. CAD drawings are made for white paper; pure blue or black disappears on a dark background. Cubory brightens such colours automatically and keeps the hue so layers stay distinguishable.
• The file is damaged. This happens when it was converted from a DWG. Best to ask the sender for a fresh export.

DXF and DWG - what is the difference?

DWG is AutoCAD’s actual working format and is not publicly documented. DXF is the documented exchange version of it. In practice that means almost every program can read DXF, far fewer can read DWG.

Cubory opens DWG too. That additionally requires LibreDWG on your system, a free tool that converts the file to DXF. If you have the choice, ask for the drawing as DXF right away.

What does it cost?

Viewing DXF costs nothing, permanently and without an account. All formats, layers and views belong to the free version. You only pay if you want to measure inside the drawing, section it or export it - that is 9 € per month, 79 € per year or 199 € once, all net.