Apps with 'Image stacking' feature
Professional digital photo management software to organize, tag, compare and process photo collections.
DeepSkyStacker is a freeware for astrophotographers that simplifies all the pre-processing steps of deep sky pictures.
Siril is an astronomical image processing tool, able to convert, pre-process images, help aligning them automatically or manually, stack them and enhance final images.
Starry Landscape Stacker makes it possible to produce landscape photographs taken at night that have both low noise and stars rendered as points.
PixInsight - Advanced Image Processing. PixInsight is a modular, open-architecture, portable image processing platform available for FreeBSD, Linux, Mac OS X and Windows.
Zerene Stacker is “focus stacking” software designed specifically for challenging macro subjects and discerning photographers. Of course it works great with simpler subjects, close-ups, and landscapes also!.
Sequator is a free software which can track stars on multiple images, align stars and stack them.