JDownloader is open source download accelerator and download manager tool written completely using Java programming. JDownload makes it easier and simpler to download files from internet including One-Click-Hosters and file hosting sites like Rapidshare.com,hotfile,megashare , Megaupload.com etc. not only for users with a premium account but also for free users who don't pay.
It also have features of downloading in multiple paralell streams, automatic captcha recognition. JDownloader can also import CCF, RSDF and the new DLC files. It supports almost all sites and "link encryption" sites . It also have a built in unrar plugin for automatical file extraction of rar and zip files. It also have HJsplit plugin which can automatically join splited parts and also split files into parts on your request.