Freeware

77.0.3865.73 has been released for Windows, Linux, Mac, and Android:
On the desktop this update “contains a number of fixes and improvements” and “includes 52 security fixes”.
“for Android: it’ll become available on Google Play over the next few weeks. This release includes stability and performance improvements.”
Download: 32-bit | 64-bit
Update Release Announcement – Desktop | Update Release Announcement – Android

This is VERY MUCH BETA. I would NOT install it (see notes).
Download: https://download.nullsoft.com/winamp/client/winamp58_3660_beta_full_en-us.exe

Winamp 5.8 Beta, Build 3660 (official)
Notes:
Some features are works-in-progress, e.g. new in_mod & out_wasapi plugins
Sorry, no CD burning, autotag or cddb features yet.
No multinational version with lang packs yet either.
Changes since unofficial build 3563
Removed ml_nowplaying; updated libogg, libvorbis, libflac & libopenmpt; copyright updates; added more genres to file info dialog; new digital cert; various other general tweaks, fixes and prep work….
Whats New:
* New: Windows Audio (WASAPI) Output plug-in (w.i.p.)
* Improved: Added an option to completely disable Winamp’s video support
* Improved: Added an auto-fullscreen option to video prefs
* Improved: Added /ENUMPLAYLISTS to the command-line support
* Improved: Windows 8.1 and 10 compatibility
* Improved: [in_mod] OpenMPT-based Module Player (replaces old MikMod player)
* Improved: [ml_playlists] Added browse path & edit title functions in Ctrl+E editor
* Improved: [Bento] Updated scrollbars and buttons and other tweaks (thanks Martin)
* Improved: [Bento & Modern skins] Added a Playlist Search feature (thanks Victor)
* Fixed: New URLs not being remembered after using Reset history in Open URL dialog
* Fixed: Various memory leaks
* Fixed: [gen_tray] Not showing correct current icon pack in preferences
* Fixed: [in_avi] Divide-by-zero crash with badly formed files (thanks ITDefensor)
* Fixed: [in_mp3] Crashing with some ID3v2 tags
* Fixed: [ml_wire] Slow loading issue
* Fixed: [ssdp] Crash on load if jnetlib was not correctly initialized
* Misc: Minimum required OS is now Win XP sp3 (Windows 7 or higher recommended)
* Misc: More general tweaks, improvements, fixes and optimizations
* Misc: Moved shared DLLs to Winamp\Shared folder
* Removed: All former “Pro” licensed functions (Winamp is now 100% freeware again)
* Removed: gen_jumpex & UnicodeTaskbarFix (making way for native implementations)
* Removed: [in_wm] DRM support
* Replaced: CD playback and ripping now using native Windows API (instead of Sonic)
* Replaced: MP3 Decoder now mpg123 based (instead of Fraunhofer)
* Replaced: AAC Decoder now using Media Foundation (Vista and higher)
* Replaced: H.264 Decoder now using Media Foundation (Vista and higher)
* Replaced: MPEG-4 Pt.2 Decoder now using Media Foundation (Vista and higher)
* Updated: [in_vorbis] libogg 1.3.3 & libvorbis 1.3.6
* Updated: [libFLAC] FLAC 1.3.2
* Updated: [libyajl] libyajl v2.1.0
* Updated: [OpenSSL] OpenSSL v1.0.1i
* Updated: [png] libpng v1.5.24