Difference between .qgs and .qgz

Question

What is the difference between the .qgz and .qgs project file formats in QGIS?

Answer 1

The other answer correctly explains that a .qgz file is primarily a zipped container containing the .qgs XML file describing the project. This is described in https://docs.qgis.org/latest/en/docs/user_manual/appendices/qgis_file_formats.html

However, the .qgz zipped container may also contain sidecar files. At the present time, these are:

1. Since 2017/2018, a .qgd file containing auxiliary storage such as custom labeling for layers in the project. See Is it safe to delete .qgd files in QGIS 3? for more information.

2. Since 2023, a project style database with extension .db (see https://github.com/qgis/QGIS/commit/c6beb62216fcfbfe3ca64283c09117da53800a98) covering styles unique to the project.

Answer 2

When I searched Google for 'qgz qgs difference' I found “QGZ” – A new default project file format for QGIS:

Last year we had the opportunity to implement ‘.QGZ’ as anew variant of the QGIS 3 project file format.

This is simply a zipped container for the QGS xml file.