Boorusphere - Yet another booru viewer for Android.
Bulk Image Downloader - With Bulk Image Downloader you can download full sized images from almost any web gallery.
Imgbrd-Grabber - Very customizable imageboard/booru browser and mass downloader, with powerful filenaming features.
Vov Picture Downloader - Download pictures from websites.
LoliSnatcher - A booru client with support for batch downloading, written in Dart/Flutter for Android but may support more platforms in the future.
WFDownloader App - A free bulk image downloader application that also serves as a multi-purpose bulk downloader for your PC.