NexusShell is a local, terminal-styled downloader for YouTube and SoundCloud. It pairs a Flask + Socket.IO backend with a dependency-free vanilla-JS frontend, wrapping yt-dlp for extraction and FFmpeg for muxing. Grab a YouTube video as MP4, pull its audio as MP3, save a SoundCloud track in its original format, or queue a whole YouTube playlist / SoundCloud set — everything runs in your local environment with no ads, accounts, or telemetry, and your download history is persisted locally in SQLite.
Paste a link and the client routes it. A single track or video hits POST /api/analyze, which calls yt_dlp.extract_info(skip_download=True) to enumerate formats; picking one sends POST /api/download, where a thread-safe QueueManager hands a DownloadTask to a daemon worker in DownloadManager. yt-dlp progress_hooks stream download_progress / download_complete / download_error events over Socket.IO to drive the live progress bar. YouTube playlists and SoundCloud sets are detected client-side, parsed flat via /api/playlist/parse, then handed to a single sequential yt-dlp job that writes to downloads/<playlist>/<index>. <title>.<ext>. Inputs are restricted to an allow-list of YouTube and SoundCloud hosts.