Apps similar to Illustail include Gallery-DL, which is free and open source. Other options are Hitomi Downloader, Imgbrd-Grabber, Booru Studio and Aria. You can choose from more than 10 Image Downloaders like Illustail for Android, Windows, Linux, Mac and iPad.
gallery-dl is a command-line program to download image galleries and collections from several image hosting sites (see https://codeberg.org/mikf/gallery-dl/src/branch/master/docs/supportedsites.md for full list).
United States
Very customizable imageboard/booru browser and mass downloader, with powerful filenaming features.
France
EU
Booru Studio is a modern and easy to use image browser and download manager for public booru galleries. It can run in its own window or in a browser tab.
GermanyEU
Japan
Boorusphere is an open source booru client written in Flutter. It supports a.o. searching, playing videos, has a theme switcher and a drawer menu, and much more.
Indonesia
Japan
Boorusama is a simple, modern and feature-rich unofficial client for Danbooru where you can explore, view and download the best anime images.
Dhaaga is a third-party app with a focus on browsing, general SNS features and chat based use cases.
India
A booru client with support for batch downloading, written in Dart/Flutter for Android but may support more platforms in the future.
PolandEU
