This only applies to the windows installer offered on our main download site.
JDownloader can be free because we offer additional software during the installation process.
This means, that there is an extra screen during the installation that explains the offer, and gives you the option to uncheck it.
If you uncheck these checkboxes, no 3rd party software will be installed.
If you installed the offer by accident, you most likely missed this screen, and clicked "continue".
You can uninstall the installed additional software in your Windows Software Control Panel, or by using a tool like this: Malwarebytes AdwCleaner
In case you prefer an installer that does not offer any optional additional software, use our adware-free installer.
If you need any further help with installing or uninstalling, please do not hesitate to contact our support: firstname.lastname@example.org