B4S File

What are B4S files and how to open them

Are you having problems opening a B4S file or are you simply curious about its contents? We're here to explain the properties of these files and provide you with software that can open or handle your B4S files.

What is a B4S file?

A .B4S file is a Winamp 3 Playlist file.

Winamp 3 Playlist files store an ordered list of media items (such as audio files or stream URLs) plus extra information about each item and about the playlist. They were written by Nullsoft's Winamp 3 media player to save which tracks are queued, what they are called, how long they are, and optional labels or titles. Because they use XML, they allow richer metadata than simple text-based playlists.

These playlist files are generated when a user saves or exports a playlist in Winamp 3. They do not contain the audio data itself, only references (paths or URLs) to media files along with metadata like the display name (title) and the length in milliseconds or samples. Other media players or tools that accept Winamp playlist formats can read them; if the referenced media files have moved or are missing, playback or listing may fail or show broken links. Over time this format has become less common as users increasingly rely on simpler or more portable playlist formats.

Files begin with an XML declaration including version "1.0", encoding "UTF-8", and the tag WinampXML as the root. Playlist-level attributes include num_entries and label. Each media item is an entry element with a Playstring attribute pointing to the file or stream. Inside each entry are child elements such as Name and Length giving the track's display title and duration. Manifest strings that help uniquely identify this format include "Nullsoft Winamp3 Version", "PLAYLIST NUM_ENTRIES", "ENTRY PLAYSTRING", "XML VERSION", "WINAMPXML", "UTF-8", "LENGTH", "LABEL", "NAME", and "STANDALONE". These signatures appear in the file at or near the start or embedded in XML tags.

How to open B4S files

Important: Different programs may use files with the B4S file extension for different purposes, so unless you are sure which format your B4S file is, you may need to try a few different programs.

While we have not verified the apps ourselves yet, our users have suggested ten different B4S openers which you will find listed below.

Last updated: August 23, 2026

Various apps that use files with this extension

These apps are known to open certain types of B4S files. Remember, different programs may use B4S files for different purposes, so you may need to try out a few of them to be able to open your specific file.

Help us help others

File.org helps thousands of users every day, and we would love to hear from you if you have additional information about B4S file formats, example files, or compatible programs. Please use the links below or email us at submit@file.org to discuss further.