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QCAD – Open Source CAD System

QCAD – Open Source CAD System


·May 21, 2022


I work at a GIS SaaS company and we use QCAD for our services. I always appriciate that they offer commercial licenses at a low price.

A few things about QCAD:

1. The coolest feature is its CLI [1] and it runs beautifully on Linux/macOS/Windows. We use it for CAD to Tile map conversion and metadata extraction in our backend.

2. It looks like the rendering engine is single-threaded and does not support GPU acceleration. So watch out opening a complex CAD file.

3. There are some compatibility issues with AutoCAD files, especially Hatch. But it mostly works great.



I just bought a QCAD CAD/CAM license to have around.

We have AutoCAD as well as DraftSight. I am happy to support this effort, particularly at such a low cost. The CAM and nesting part might actually find immediate use driving our laser cutting/engraving machine. I haven't installed it yet, will play with it tomorrow.

Any clone or alternative to AutoCAD eventually has to implement LISP support. DraftSight has it.

We have fairly extensive AutoLISP code that turns ACAD into quite a powerful tool for the right type of job. The codebase was developed for the design and construction of large technical installations where you have to manage thousands of cables of different types, calculate lengths, produce wiring lists, labels, etc.


What aspect of GIS work has crossover with CAD?


As a civil engineer: Essentially ALL of my CAD work basically is GIS. Only architectural drawings which are a tiny fraction of Civil drawings are an exception to that rule.

Civil3D is basically the industry standard and it is a GIS software.

We import many different GIS files into every drawing: property lines, jurisdicitons, roads, pipe networks, streams, topography etc.

You have to be a little careful when incorporating survey data (ground vs grid issues).

Then we draw onto various state plane projected coordinate systems. Creating pipe networks, road corridors, 3D grading and surfaces.

There's a bunch of analysis that comes out of that work as well. The beauty of Civil3d is that much of the analysis can be done IN the drawing. For obvious reasons that saves a lot of time.


That sounds like very interesting work and powerful software. I'm a little educated in other GIS software like QGIS and Arc, but don't have a true engineering background by any stretch. CAD work with integrated real world GIS data seems like it would be novel


CAD is used for architecture and civil engineering. Specifically we need to map a civil drawing (CAD file) to something like Google Map.

You can easily see the use case from our competitior website:


GIS is CAD but on a projection system instead of a perfectly flat 2D plane.


Any WYSIWYG GIS app (as software) is a sorta of WYSIWYG CAD apps.


Very cool, it's awesome to see more offerings in the open-source CAD space. Even though this doesn't compare with, say, FreeCAD (being 2d-only), it looks like the features it does provide are fairly polished based on the description. It's nice that it comes with built-in CAM tooling.

One thing that I'm wondering about is a constraint-solving system - the documentation doesn't mention anything about sketch constraints. Usually a constraint system is pretty important in CAD work, so I wonder if there's plans to add one.


> One thing that I'm wondering about is a constraint-solving system - the documentation doesn't mention anything about sketch constraints.

If you a looking constraint solver based 2D/3D CAD, take a look on SolveSpace.[0]

SolveSpace's constraint solver actually also (partially) ported for FreeCAD & Blender.[1]

Here are my SolveSpace showcases.[2]





What is the advantage of SolveSpace over FreeCAD for 3D parts? I tried it once before and it seems substantially less feature-complete than FreeCAD.

And FreeCAD already has constraint solving in sketches. The tweet you've linked is about constraint solving in a non-default workbench (LinkStage3) that allows you to define constraints between separate parts when bringing them into a single assembly.


>> What is the advantage of SolveSpace over FreeCAD for 3D parts?

If you compare a list of features, there is probably no advantage.

People use solvespace because it is easier to use, has minimal UI which encourages working directly with the part. Its non-modal, meaning no workbenches, project files, or other overhead. As someone said, they actually enjoy using it.

It's good enough for many things, and the simplicity and fun make it the tool of choice for a small but growing community.

People use FreeCAD because it gets the job done, but people love Solvespace because... well because its Solvespace.


FreeCAD has good parametric 2D modelling.

QCAD can't do constraints.


I love QCAD, but I am very curious if there are any 2D modeling/drawing programs with constraints. Let me know if you've used on and would recommend it.

Can FreeCAD export the 2D drawings?


Do you mean 2D-only CAD programs? Because you don't have to go 3D with SolveSpace, nor do you have to go 3D with CAD Sketcher for Blender (it uses a Python port of the SolveSpace's solver).

Yes, FreeCAD can export 2D. See


For those actually looking for the source code (not the first thing that's shown on the site):


Weird. I just installed this Thursday. I was just looking for a graph paper simulator with +Y up, that would let me do things with lines and points, and easily read any coordinates. This was the only free solution I found.

Exactly like Blender (which I use daily) it does every little thing in the most backwards, unintuitive way possible, but if you patiently learn its asinine way of doing things, it becomes very useful.


qcad is great. I've been using it for at least 15 years. I use it to plan my woodworking projects. The keyboard controls and 2d nature make it super fast to try out ideas and to become clear how the joinery will come together. I tried freecad a few times but I've always gone back to qcad.


Yeah, I love that practically everything has a keyboard shortcut. Makes working with it a breeze.


Is this the clone of AutoCAD 2000 from the 2004 era? That was free, then proprietary, then forgotten.


I had similar question when I was reading the GIMP 3.0 thread the other day. Are there any legal issues, if someone made Open Source CAD that has a 99.999% similar UI to AutoCAD or in GIMP's case Photoshop?


How is it an AutoCAD 2000 clone if it's 2D only? AutoCAD could do 3D really well in the 90s if not earlier... (not parametric, but still)


Well it's released in 1999 and it is still actively maintained. It's awesome to see a long time commitment.


It is. But I was amused when I encountered it and saw that it repeated design decisions made to cram AutoCAD into a DOS machine. Do they still have "redraw" and "regen?"?


Not sure this is what you are looking for, but there is. I have never used this though:


Yes. I use qcad/librecad very infrequently.

But I used it for the first time for a renovation of my apartment in 2004 and it isjust great that when I was discussing a renovation with a neighbor I could still use it with the old files.


I have used it a lot under Linux. It's easy to get objects perfectly aligned. Although I've experienced problems with really large files.

I have even used it for design of complex footprints for electronic components before redoing them in KiCAD (electronic design software), because I found QCAD to be less clunky.


In my system it is called "librecad". I guess qcad is non-free somehow.


LibreCAD is a fork [0] of QCAD Community Edition. It looks very similar, but it is actually a separate piece of software.

The biggest difference I see between these two is UI and the pace of development. LibreCAD is still being worked on, but the latest stable release was in 2016. Last patch for QCAD has been released four days ago.

Personally, I prefer QCAD to LibreCAD. Both are quirky to use, but QCAD is at least a little bit less quirky. If you are coming from AutoCAD, then both will be equally confusing.

[0] Maybe not literally, README file available in LibreCAD repo declares that "LibreCAD is a 2D CAD drawing tool based on the community edition of QCAD." On the other hand, Libre Arts article [1] calls it fork.



The other big difference is DWG compatibility for interop with AutoCAD. QCAD has good DWG compat, but only in the commercial version.

LibreCAD has not-great DWG support and is free. Last I remember reading about it, they were looking to get better DWG support via the LibreDWG library, but they needed to strip out and fully rewrite a bunch of old QCAD code to achieve that, due to licensing issues.


> Personally, I prefer QCAD to LibreCAD. Both are quirky to use, but QCAD is at least a little bit less quirky.

LibreCAD in same time has a better performance with big/complex drawings, than QCAD.


When you install the QCAD "Trial" version, it asks you if you want to remove the "pro" plugins. After that, it becomes free.


Hmm, the license page mentions the GPL.


It bothers me a bit that QCad and the LibreCAD folks have split. I think I understand why, but it seems sub-optimal for both.


Not quite Open Source though.


LibreCAD is a fork of QCAD that aims to be 100% free.


I was using it recently to fixup the output of open scad!


Wow it works on mac? Will have to give it a try


Yes it works on the latest macOS very well. They recently released native M1 version too.