Rating and comments for QCad Community Edition

the diference is so big, Qcad is so bad if we compare with autocad

QCad is not bad. I don't think that anyone should fully emulate AutoCad - because it is a bit bloated. But it is the 800 lb gorilla. I would love to see autodesk consider a move to linux, but that seems unlikely. They've cast their lot with Windows.

QCad is OK for simple tasks. It actually works quite well for viewing and printing .dxf files on Linux.

QCad is based on QT and this makes it a multiplatform app. Apart from Linux, QCad is also available in Windows and Mac OSX. My company is doing "real" work with it, mostly 2D mechanical design.

It needs paying. How can it be open source?

It's not Open Source, it's comercial

It is under the GPL with the community version, just scroll a bit in the downloads section. They have a lower quality, free (non-trial) version.