I am here posting links of Free and Opensource Download Manager, no paid/trial download managers.
1. Eagleget
http://www.eagleget.com/
2. Neat Download Manager
https://www.neatdownloadmanager.com/
3. Xtreme Download Manager (XDM)
https://xtremedownloadmanager.com/
4. Free Download Manager (FDM)
https://www.freedownloadmanager.org/
5. uGet
https://ugetdm.com/
6. Persepolis Download Manager
https://persepolisdm.github.io/
7. AM Downloader
https://mozib.io/amdownloader/
8. Motrix
https://motrix.app/
9. MiniGet (Official Site Dead, Latest Version 1.1.10.1806 is Below)
https://www.softportal.com/get-33983-miniget.html
10. FireDM
https://pypi.org/project/FireDM/
11. AriaNg GUI
https://www.npmjs.com/package/aria-ng-gui
There are lot of other download managers too, but there are too much issues or they do not support https links.
Jdownloader, Leechget, Flashget, DAM, GetGo download manager, migmigi and etc
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