SiriL
Price: Free
Siril is a free astrophotography software that allows you to pre-process and process images from any camera (CCD, planetary camera, webcam, etc.). The images must be converted to 32-bit FITS format, which Siril uses natively. Without prior conversion, it is also possible to use the SER format (limited to 16 bits), which is commonly used during "fast" planetary or deep-sky acquisitions.
Because it is based on the GNOME environment, it can run on a variety of platforms, including Linux, FreeBSD, macOS, and Windows.
DeepSkyStacker
Price: Free
DeepSkyStacker is a free piece of software for astrophotographers that simplifies the pre-processing of deep-sky images.
DeepSkyStacker is a portable software application designed for astrophotographers who want to process deep-sky images in real-time. It supports popular file formats such as JPEG, BMP, PNG, TIFF, and RAW images.
Adobe Photoshop
Price: Subscription
Adobe Photoshop is the best image editor in the photography market, and it can be used for a variety of purposes, including astrophotography.
Photoshop has a plethora of features that can help you improve your images significantly.
GIMP
Price: Free
Related: Customize Gimp For Photoshop Users (Gimp to Photoshop)
GIMP is very similar to Photoshop in terms of features and functionality; the only difference is that gimp is destructive editing software; however, gimp may get this feature in the future, but for now, gimp is more than enough to meet your astrophotography needs.
Affinity Photo
Price: Decent Price
Affinity Photo, like Photoshop, is a very capable image processing tool that can do almost everything Photoshop can do. The only limitation of Affinity Photo is that it lacks a specialized astrophotography tool, but it can still do almost everything related to image manipulation.
