AppImage (any distro)
Download the AppImage from the download section, then run chmod +x PurffleGrab*.AppImage and open it.
Purffle / PurffleGrab / Guides / Downloader for Linux
A real desktop app for Ubuntu, Fedora, Debian, Arch and Mint — yt-dlp and FFmpeg built in, no terminal needed.
PurffleGrab gives Linux a proper desktop YouTube and Spotify downloader: a window instead of a terminal, MP4 up to 4K and 8K, MP3 and FLAC, playlists, channel follows and a built-in player. It runs yt-dlp underneath, so you get the same reliability without remembering any flags.
Download the AppImage from the download section, then run chmod +x PurffleGrab*.AppImage and open it.
Download the .deb and run sudo apt install ./purfflegrab*.deb. It appears in your app menu.
Sign in with your email, paste a YouTube or Spotify link, pick a preset, download.

If you're happy in a terminal, yt-dlp alone is free, open source and does everything. PurffleGrab is for when you'd rather click: it adds a track picker, Spotify playlists with proper tags, a queue that resumes after a restart, channel follows, a Library and a player. Many people use both.
Free gives you 67 downloads a month up to 1080p with a free account (just your email, no card), and new accounts get 3 days of Pro free. Pro passes start at $1.49 (₹49) a week, you pay once and they never renew.
The AppImage runs on most 64-bit desktops (Ubuntu, Fedora, Debian, Arch, Mint, Pop!_OS and others). There's also a .deb for Ubuntu, Debian and Mint.
No. Both are bundled, and yt-dlp updates itself.
The app isn't, but the download engine it uses, yt-dlp, is. If you prefer a fully open-source command-line tool, yt-dlp on its own is excellent.
Downloading can breach a site's terms of service and may infringe copyright where you live. Clearly fine: your own uploads, Creative Commons and public-domain material, and content you're licensed to keep offline.